SCons: Move platform logo/run icon to export folder

Follow-up to #75932.
Since these icons are only used by the export plugin, it makes sense to
move them and generate the headers there.

The whole `detect.is_active()` logic seems to be a leftover from before
times, as far back as 1.0-stable it already wasn't used for anything.

So I'm removing it and moving the export icon generation to
`platform_methods`, where it makes more sense.

platform/web/export/export_plugin.cpp

@@ -30,8 +30,8 @@
 
 #include "export_plugin.h"
 
-#include "../logo_svg.gen.h"
-#include "../run_icon_svg.gen.h"
+#include "logo_svg.gen.h"
+#include "run_icon_svg.gen.h"
 
 #include "core/config/project_settings.h"
 #include "editor/editor_scale.h"

platform/web/export/logo.svg

@@ -0,0 +1 @@
+<svg height="32" width="32" xmlns="http://www.w3.org/2000/svg"><path d="M7 5h18v21H7z" fill="#fff"/><path d="M3.143 1 5.48 27.504 15.967 31l10.553-3.496L28.857 1zM23.78 9.565H11.473l.275 3.308h11.759l-.911 9.937-6.556 1.808v.02h-.073l-6.61-1.828-.402-5.076h3.195l.234 2.552 3.583.97 3.595-.97.402-4.165H8.788L7.93 6.37h16.145z" fill="#eb6428"/></svg>

platform/web/export/run_icon.svg

@@ -0,0 +1 @@
+<svg height="16" width="16" xml:space="preserve" xmlns="http://www.w3.org/2000/svg"><path d="M3.143 1 5.48 27.504 15.967 31l10.553-3.496L28.857 1ZM23.78 9.565H11.473l.275 3.308h11.759l-.911 9.937-6.556 1.808v.02h-.073l-6.61-1.828-.402-5.076h3.195l.234 2.552 3.583.97 3.595-.97.402-4.165H8.788L7.93 6.37h16.145Z" fill="#eb6428" style="fill:#e0e0e0;fill-opacity:1" transform="translate(.586 .586) scale(.46337)"/></svg>