highlight function names

[serkonda7]

Note: applies to Function and Sub

• declaration
• simple call
• call using Call keyword
• call from other module Call OtherMod.Func()

Due to VBA syntax having many ambiguities, a proper implementation of this feature might require integration of a language server.
However I'm not aware of an existing VBA language server to use.

Ambiguity

• array declaration and indexing syntax (see Array declaration and index improperly tokenized as function name #52)