feat: add C#, Go, Java, C, C++, Ruby language support

[pszymkowiak]

Summary

Parser now supports 10 languages (was 4):

Language	Extensions	Symbols extracted
TypeScript	.ts, .tsx	functions, classes, methods, interfaces, types, enums
JavaScript	.js, .jsx	functions, classes, methods
Rust	.rs	functions, structs, enums, traits, impls, types
Python	.py	functions, classes
C#	.cs	methods, classes, interfaces, structs, enums, namespaces
Go	.go	functions, methods, types
Java	.java	methods, classes, interfaces, enums
C	.c, .h	functions, structs, enums, typedefs
C++	.cpp, .cc, .cxx, .hpp	functions, classes, structs, enums, namespaces
Ruby	.rb	methods, singleton methods, classes, modules

Test plan

• 53 tests passing (6 new for new languages)
• cargo clippy clean