Leverage Rust 1.79, 1.80 (#9498)

This commit is a follow-up to #9496 to leverage various APIs that the
workspace now has access to. For example most dependencies on the
`once_cell` crate are now rem

Leverage Rust 1.79, 1.80 (#9498)

This commit is a follow-up to #9496 to leverage various APIs that the
workspace now has access to. For example most dependencies on the
`once_cell` crate are now removed in favor of the types stabilized in
the standard library: `LazyLock` and `LazyCell`. One dependency remains
in the `wasmtime` crate due to the `get_or_try_init` not being stable
yet.

Some additional helper methods on raw pointer slices are also available
for removing a few minor `unsafe` blocks.

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