perf: Pre-compile and share glob patterns across packages

When multiple packages share the same task inputs (e.g. src/**), each
package was independently compiling identical wax::Glob patterns (which
internally compile regexes). This adds a GlobSet type that compiles
patterns once and reuses them across all packages with the same inputs.

- Add GlobSet to globwalk: compile-once, walk-many API for glob patterns
- Add precompiled SCM methods that accept shared GlobSets
- Group packages by glob signature in calculate_file_hashes to share
  compiled patterns via Arc<GlobSet>
- Skip symlink_metadata syscalls for known config file literals
- Handle directory-literal expansion at walk time in GlobSet
- Fix turborepo-run-cache missing git2 feature on turborepo-scm dep

Author: anthonyshew