[LesterEvSe]

parse.rs had grown to approximately 4 500 lines. this PR splits it into smaller files. There is no change in behavior or public API.

src/parse/
├── mod.rs              parse tree node types (Program, Expression, Call, ...), their accessors, ExprTree
├── pipeline.rs         ParseFromStr, ParseFromStrWithErrors: prescan, lex, parse, feature check
├── display.rs          Display impls for the parse tree
├── lossless.rs         ParsedSource and parse_with_errors_for_fmt, for formatters (feature "fmt")
├── arbitrary_impls.rs  Arbitrary impls for fuzzing (feature "arbitrary")
├── grammar/
│   ├── mod.rs          the ChumskyParse trait, identifier parsers, shared recovery helpers
│   ├── program.rs      Program, items, functions, use declarations, modules
│   ├── types.rs        AliasedType, TypeAlias, EnumDeclaration
│   ├── statement.rs    Statement, Assignment, Pattern
│   ├── expression.rs   Expression, SingleExpression, EnumConstruction
│   ├── call.rs         Call, CallName
│   └── matching.rs     MatchPattern, Match, EnumMatch
└── tests/              parser tests for the regular and the lossless (fmt) entry points

Checklist

• New or changed language features are used in fixtures/kitchen_sink.simf (see its header).

[KyrylR]

ACK 258e027; successfully ran local tests

Ran tests and CI on every commit

[LesterEvSe]

Since it is a refactoring without any API changes, we merged it as it is.
This will help us continue our work on errors: https://community.simplicity-lang.org/t/simplicityhl-now-reports-more-than-one-error-per-run/94

[apoelstra]

Guys, please don't merge 10000 line diffs without any input from me.

[LesterEvSe]

Ok, sorry for that