feat(fmt): rewrite formatter using Solar and a structured algorithm

[DaniPopes]

Rewrite forge-fmt entirely to use Solar as the Solidity/Yul parser and AST, and using a structured pretty-printing algorithm.

The language-agnostic implementation of the pretty-printer (src/pp) is based on rustc_ast_pretty and prettyplease, both MIT and Apache licensed. See prettyplease's README for algorithm notes.

The goal of this PR is to make progress with #9317, and fixing existing issues with the formatter while trying to maintain compatibility as much as possible.

This PR will not be replacing the formatter yet, opting to create a separate crate crates/fmt-2 to reduce unrelated changes and aid with review. A follow-up PR will replace crates/fmt and deal with fallout in-tree.

WIP

Progress

Tests:

13 passed; 40 failed; 1 ignored

Implementation:

• items
  • pragma
  • import
  • using
  • contract/interface/library
  • function/modifier
  • variable declaration
  • struct
  • enum
  • UDVT
  • error
  • event
• types
• expressions
  • literals
  • ...
• statements
  • if
  • while
  • do while
  • for
  • try-catch
  • ...
• yul
  • expressions
  • statements
  • functions

Other:

• Update README.md
• Refactor printing delimited groups to handle span/comments
• Print docs that get discarded during parsing like other comments
• Add a non-fatal error that returns the formatted source with the errors
• Add snapshot infra to tests to automatically update 'expected' files

Configs:

• line_length: usize
• tab_width: usize
• bracket_spacing: bool
• int_types: IntTypes
• multiline_func_header: MultilineFuncHeaderStyle
• quote_style: QuoteStyle
• number_underscore: NumberUnderscore
• hex_underscore: HexUnderscore
• single_line_statement_blocks: SingleLineBlockStyle
• override_spacing: bool
• wrap_comments: bool
• ignore: Vec<String>
• contract_new_lines: bool
• sort_imports: bool

Issues

Issues that will be fixed with the new implementation. Not closed by this PR, but by the follow-up that will hook the new implementation up; see paragraph above.

• Fixes\ feat(fmt): allow line_length to be a hard requirement #4450
• Fixes\ Extend capabilities of Foundry formatter to be compatible with Solidity's official style guide #6147
• Fixes\ feat(forge fmt): sorting of imports adds newlines in groups #7944
• Fixes\ bug(forge fmt): ignores forgefmt: disable-next-line in argument lists #8557
• Fixes\ feat(fmt): support transient keyword by moving to Solar #9088
• Fixes\ Forge fmt does not work with custom storage layouts 0.8.29 #10244