Explicitly use 'ast or 'arena instead of 'a for lifetime specifier for data structures related to arena.

[hyf0]

rustc use 'tcx to explicitly show what data is related to arena.

See https://rustc-dev-guide.rust-lang.org/memory.html#the-tcx-and-how-it-uses-lifetimes for details.

Currently, oxc uses 'a for lifetime specifier, which could be very misunderstood for 'a is a commonly used name for lifetime specifier just like meaningless variable names foo or bar.

It's hard to distinguish whether a structure with lifetimes is due to hold data related to arena or just a reference.