rustdoc: Remove most fields from ExternalCrate

[jyn514]

Once #84304 is fixed, I can get rid of ExternCrate altogether in favor of CrateNum, but in the meantime, this shrinks ExternalCrate quite a lot.

This might hurt compile-times; if it does, I can add primitive and keyword queries. I expect this to improve compilemem.

Helps with #76382.

r? GuillaumeGomez

[jyn514]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

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

[bors]

⌛ Trying commit 6c6bd88 with merge 336b6b63c7dd2281785650fb6ce1c4066cffe416...

[bors]

☀️ Try build successful - checks-actions
Build commit: 336b6b63c7dd2281785650fb6ce1c4066cffe416 (336b6b63c7dd2281785650fb6ce1c4066cffe416)

[rust-timer]

Queued 336b6b63c7dd2281785650fb6ce1c4066cffe416 with parent 5f1aeb5, future comparison URL.

[rust-timer]

Finished benchmarking try commit (336b6b63c7dd2281785650fb6ce1c4066cffe416): 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]

Interesting - max RSS looks like noise, but up to -3.8% on instruction count.

[GuillaumeGomez]

Thanks!

@bors: r+

[bors]

📌 Commit 6c6bd88 has been approved by GuillaumeGomez

[bors]

⌛ Testing commit 6c6bd88 with merge 38abe86bb3b0144123be65349c2afb1a94eb3ed4...

[bors]

💔 Test failed - checks-actions

[rust-log-analyzer]

A job failed! Check out the build log: (web)(plain)

Click to see the possible cause of the failure (guessed by this bot)

[jyn514]

dist-x86_64-apple-alt failed without logs :/

@bors retry

[bors]

⌛ Testing commit 6c6bd88 with merge 484c619...

[bors]

☀️ Test successful - checks-actions
Approved by: GuillaumeGomez
Pushing 484c619 to master...