Auto merge of #117377 - dtolnay:deprecatedsince, r=cjgillot

Store #[deprecated] attribute's `since` value in parsed form

This PR implements the first followup bullet listed in https://github.com/rust-lang/rust/pull/117148#issue-1960240108.

We centralize error handling to the attribute parsing code in `compiler/rustc_attr/src/builtin.rs`, and thereby remove some awkward error codepaths from later phases of compilation that had to make sense of these #\[deprecated\] attributes, namely `compiler/rustc_passes/src/stability.rs` and `compiler/rustc_middle/src/middle/stability.rs`.