Improve/lower build time about ogre-next HOT 4 OPEN

The following commits aim at reducing STL header dependencies:

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from ogre-next.

New data from ClangBuildAnalyzer

It shows we spend a lot of time instantiating ParamDictionaryMap.
This map is used in StringInterface and Resource derives from it. As a result it ends up being used everywhere.

ParamDictionaryMap is actually used to define msDictionary which is a global static variable.
It doesn't have to be declared in class StringInterface.

Additionally, moving createParamDictionary to a cpp file instead of a header should allow us to completely remove ParamDictionaryMap & msDictionary from the header definition.

OgreGpuProgram.h & OgreGpuProgramParams.h are also expensive, which are included by OgreRenderable.h and hence everywhere.

That's only needed because of _updateCustomGpuParameter. Slightly refactoring that function to use forward declarations should allow us to remove that header.

from ogre-next.

Don't know if you're aware of it, but this is a brute force tool to clean useless #include. It basically tries to build a project/solution removing headers one by one checking whether errors are raised or not.

from ogre-next.

I was aware of these tools but that one in particular looks very user friendly, thanks!

BTW I should also mention we should try Bloaty McBloatface. Example on libfmt

from ogre-next.