SCons: Format buildsystem files with psf/black

Configured for a max line length of 120 characters.

psf/black is very opinionated and purposely doesn't leave much room for
configuration. The output is mostly OK so that should be fine for us,
but some things worth noting:

- Manually wrapped strings will be reflowed, so by using a line length
  of 120 for the sake of preserving readability for our long command
  calls, it also means that some manually wrapped strings are back on
  the same line and should be manually merged again.

- Code generators using string concatenation extensively look awful,
  since black puts each operand on a single line. We need to refactor
  these generators to use more pythonic string formatting, for which
  many options are available (`%`, `format` or f-strings).

- CI checks and a pre-commit hook will be added to ensure that future
  buildsystem changes are well-formatted.

editor/SCsub

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-Import('env')
+Import("env")
 
 env.editor_sources = []
 
@@ -16,24 +16,24 @@ def _make_doc_data_class_path(to_path):
     g.write("static const int _doc_data_class_path_count = " + str(len(env.doc_class_path)) + ";\n")
     g.write("struct _DocDataClassPath { const char* name; const char* path; };\n")
 
-    g.write("static const _DocDataClassPath _doc_data_class_paths[" + str(len(env.doc_class_path) + 1) + "] = {\n");
+    g.write("static const _DocDataClassPath _doc_data_class_paths[" + str(len(env.doc_class_path) + 1) + "] = {\n")
     for c in sorted(env.doc_class_path):
-        g.write("\t{\"" + c + "\", \"" + env.doc_class_path[c] + "\"},\n")
+        g.write('\t{"' + c + '", "' + env.doc_class_path[c] + '"},\n')
     g.write("\t{NULL, NULL}\n")
     g.write("};\n")
 
     g.close()
 
 
-if env['tools']:
+if env["tools"]:
     # Register exporters
     reg_exporters_inc = '#include "register_exporters.h"\n'
-    reg_exporters = 'void register_exporters() {\n'
+    reg_exporters = "void register_exporters() {\n"
     for e in env.platform_exporters:
         env.add_source_files(env.editor_sources, "#platform/" + e + "/export/export.cpp")
-        reg_exporters += '\tregister_' + e + '_exporter();\n'
+        reg_exporters += "\tregister_" + e + "_exporter();\n"
         reg_exporters_inc += '#include "platform/' + e + '/export/export.h"\n'
-    reg_exporters += '}\n'
+    reg_exporters += "}\n"
 
     # NOTE: It is safe to generate this file here, since this is still executed serially
     with open("register_exporters.gen.cpp", "w", encoding="utf-8") as f:
@@ -50,12 +50,12 @@ if env['tools']:
 
     for d in doc_dirs:
         try:
-            for f in os.listdir(os.path.join(env.Dir('#').abspath, d)):
+            for f in os.listdir(os.path.join(env.Dir("#").abspath, d)):
                 docs.append("#" + os.path.join(d, f))
         except OSError:
             pass
 
-    _make_doc_data_class_path(os.path.join(env.Dir('#').abspath, "editor"))
+    _make_doc_data_class_path(os.path.join(env.Dir("#").abspath, "editor"))
 
     docs = sorted(docs)
     env.Depends("#editor/doc_data_compressed.gen.h", docs)
@@ -63,32 +63,36 @@ if env['tools']:
 
     import glob
 
-    path = env.Dir('.').abspath
+    path = env.Dir(".").abspath
 
     # Editor translations
     tlist = glob.glob(path + "/translations/*.po")
-    env.Depends('#editor/editor_translations.gen.h', tlist)
-    env.CommandNoCache('#editor/editor_translations.gen.h', tlist, run_in_subprocess(editor_builders.make_editor_translations_header))
+    env.Depends("#editor/editor_translations.gen.h", tlist)
+    env.CommandNoCache(
+        "#editor/editor_translations.gen.h", tlist, run_in_subprocess(editor_builders.make_editor_translations_header)
+    )
 
     # Documentation translations
     tlist = glob.glob(env.Dir("#doc").abspath + "/translations/*.po")
-    env.Depends('#editor/doc_translations.gen.h', tlist)
-    env.CommandNoCache('#editor/doc_translations.gen.h', tlist, run_in_subprocess(editor_builders.make_doc_translations_header))
+    env.Depends("#editor/doc_translations.gen.h", tlist)
+    env.CommandNoCache(
+        "#editor/doc_translations.gen.h", tlist, run_in_subprocess(editor_builders.make_doc_translations_header)
+    )
 
     # Fonts
     flist = glob.glob(path + "/../thirdparty/fonts/*.ttf")
     flist.extend(glob.glob(path + "/../thirdparty/fonts/*.otf"))
     flist.sort()
-    env.Depends('#editor/builtin_fonts.gen.h', flist)
-    env.CommandNoCache('#editor/builtin_fonts.gen.h', flist, run_in_subprocess(editor_builders.make_fonts_header))
+    env.Depends("#editor/builtin_fonts.gen.h", flist)
+    env.CommandNoCache("#editor/builtin_fonts.gen.h", flist, run_in_subprocess(editor_builders.make_fonts_header))
 
     env.add_source_files(env.editor_sources, "*.cpp")
 
-    SConscript('debugger/SCsub')
-    SConscript('fileserver/SCsub')
-    SConscript('icons/SCsub')
-    SConscript('import/SCsub')
-    SConscript('plugins/SCsub')
+    SConscript("debugger/SCsub")
+    SConscript("fileserver/SCsub")
+    SConscript("icons/SCsub")
+    SConscript("import/SCsub")
+    SConscript("plugins/SCsub")
 
     lib = env.add_library("editor", env.editor_sources)
     env.Prepend(LIBS=[lib])