[rustdoc] Calculate stability, const_stability, and deprecation on-demand

[jyn514]

Previously, they would always be calculated ahead of time, which bloated the size of clean::Item.

Builds on #80090 and should not be merged before. Helps with #79103 and #76382.

cc #80014 (comment)

This brings Item down to 568 bytes, down from 616.

[rust-highfive]

r? @GuillaumeGomez

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[jyn514]

Oops, I never ran perf on this.

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

[bors]

⌛ Trying commit 1523f67 with merge bf5ffc1e18462e62769c4e09320da201c8a72ac6...

[bors]

☀️ Try build successful - checks-actions
Build commit: bf5ffc1e18462e62769c4e09320da201c8a72ac6 (bf5ffc1e18462e62769c4e09320da201c8a72ac6)

[rust-timer]

Queued bf5ffc1e18462e62769c4e09320da201c8a72ac6 with parent 353f3a3, future comparison URL.

@rustbot label: +S-waiting-on-perf

[rust-timer]

Finished benchmarking try commit (bf5ffc1e18462e62769c4e09320da201c8a72ac6): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf

[jyn514]

Ooh, very nice! -3.5% on instruction counts, max of -2.9% on max-rss.

@bors r=GuillaumeGomez rollup=never

[bors]

📌 Commit 1523f67 has been approved by GuillaumeGomez

[bors]

⌛ Testing commit 1523f67 with merge 18b745e...

[bors]

☀️ Test successful - checks-actions
Approved by: GuillaumeGomez
Pushing 18b745e to master...