microwave: Spec compliant TOML parser for Zig.

This is a spec-compliant TOML parser for Zig. According to the README, the following parsers are available:

• Parser API - for parsing an entire TOML file into a tree-like structure
• Populate API - for mapping a TOML file into a given struct
• Stringify API - for writing TOML files from a tree or given struct
• Write Stream API - for building TOML files safely with debug assertions
• Tokeniser/Scanner API - for iterating through a TOML file for each significant token