Better premake project

[otavepto]

• wrap mbedtls includes to avoid build warnings
• wrap proto includes to avoid build warnings
• move gamepad to libs/
• build proto files in a separate folder outside dll/
• add all post_build and docs files, for visibility in visual studio
• add missing ConvertUTF.c (not sure how simpleini was compiling before)
• refactor how files are collected to ensure everything is added

this makes almost everything visible in visual studio including deps headers + fixes all external warnings

[Detanup01]

you forgot to not include libs\detours\uimports.cc in steamclient_experimental win api_experimental win

[otavepto]

I forgot about the effect of filter, had to disable all filters first with filter {}