Reorganize code related to editor theming

This change introduces a new EditorThemeManager class
to abstract theme generatio and its subroutines.

Logic related to EditorTheme, EditorColorMap, and editor
icons has been extracted into their respective files with
includes cleaned up.

All related files have been moved to a separate folder to
better scope them in the project. This includes relevant
generated files as well.

editor/editor_builders.py

@@ -3,6 +3,7 @@
 All such functions are invoked in a subprocess on Windows to prevent build flakiness.
 
 """
+
 import os
 import os.path
 import shutil
@@ -49,34 +50,6 @@ def make_doc_header(target, source, env):
     g.close()
 
 
-def make_fonts_header(target, source, env):
-    dst = target[0]
-
-    g = open(dst, "w", encoding="utf-8")
-
-    g.write("/* THIS FILE IS GENERATED DO NOT EDIT */\n")
-    g.write("#ifndef _EDITOR_FONTS_H\n")
-    g.write("#define _EDITOR_FONTS_H\n")
-
-    # Saving uncompressed, since FreeType will reference from memory pointer.
-    for i in range(len(source)):
-        with open(source[i], "rb") as f:
-            buf = f.read()
-
-        name = os.path.splitext(os.path.basename(source[i]))[0]
-
-        g.write("static const int _font_" + name + "_size = " + str(len(buf)) + ";\n")
-        g.write("static const unsigned char _font_" + name + "[] = {\n")
-        for j in range(len(buf)):
-            g.write("\t" + str(buf[j]) + ",\n")
-
-        g.write("};\n")
-
-    g.write("#endif")
-
-    g.close()
-
-
 def make_translations_header(target, source, env, category):
     dst = target[0]