Rollup merge of #138682 - Alexendoo:extra-symbols, r=fee1-dead

Allow drivers to supply a list of extra symbols to intern

Allows adding new symbols as `const`s in external drivers, desirable in Clippy so we can use them in patterns to replace code like https://github.com/rust-lang/rust/blob/75530e9f72a1990ed2305e16fd51d02f47048f12/src/tools/clippy/clippy_lints/src/casts/cast_ptr_alignment.rs#L66

The Clippy change adds a couple symbols as a demo, the exact `clippy_utils` API and replacing other usages can be done on the Clippy side to minimise sync conflicts

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try-job: aarch64-gnu

Author: Zalathar