Moves from `@lifetime` to `@_lifetime` and the `LifetimeDependence`
experimental feature to `Lifetimes`.

* Add parser for LEB128 integers.
* Add tests for LEB128 overflow. Fixed overflow check and added a max byte count check.

)

The current (see below) version of the binary might be causing
compilation issues. This change skips it for now.

https://download.swift.org/prebuilts/swift-syntax/600.0.1/swift-6.2-DEVELOPMENT-SNAPSHOT-2025-09-06-a-MacroSupport-ubuntu_jammy_x86_64.tar.gz

This change adds three `ParserSpan.extracting` APIs that yield new
`ParserSpan` instances that have their internal span boundaries shrunk
to fit, instead of just insetting the boundaries at the `ParserSpan`
level. An extracted span can be passed off to a parsing function
without worry that an absolute seek will go beyond the visible
boundaries of the span.

This adds two parsers that produces inline arrays:
- a byte-based parser that fills an InlineArray with `UInt8` values
- a parser closure-based parser that fills an InlineArray with
  the results of the parser, called the required number of times.

…e#38)