Changes:
* EngineDebugger is exposed to gdscript. Game side of communication can be implemented through it.
* EditorDebuggerPlugin is added which handles the editor side of communication.
Custom monitors can be added/removed/checked using `Performance.add_custom_monitor`/`Performance.remove_custom_monitor`/`Performance.has_custom_monitor`
The value can be viewed in the `Monitor` tab of Debugger.
Text before `/` is used to categorize the custom monitor.
`EditorPerformanceProfiler` class is created to separate logic from `ScriptEditorDebugger`
User can click on the graph of monitors to read the value at that point.
Graph includes intermediate base lines.
Which means that reduz' beloved style which we all became used to
will now be changed automatically to remove the first empty line.
This makes us lean closer to 1TBS (the one true brace style) instead
of hybridating it with some Allman-inspired spacing.
There's still the case of braces around single-statement blocks that
needs to be addressed (but clang-format can't help with that, but
clang-tidy may if we agree about it).
Part of #33027.
For us, it practically only changes the fact that `A<A<int>>` is now
used instead of the C++03 compatible `A<A<int> >`.
Note: clang-format 10+ changed the `Standard` arguments to fully
specified `c++11`, `c++14`, etc. versions, but we can't use `c++17`
now if we want to preserve compatibility with clang-format 8 and 9.
`Cpp11` is still supported as deprecated alias for `Latest`.
