Move top part of print_item to Tera templates

[jsha]

Part of #84419.

This moves the first line of each item page (E.g. Struct foo::Bar .... 1.0.0 [-][src] into a Tera template.

I also moved template initialization into its own module and added a small macro to reduce duplication and opportunity for errors.

[rust-highfive]

r? @CraftSpider

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[GuillaumeGomez]

Thanks for the PR and the answers!

r=me once CI pass

[jsha]

@bors r=GuillaumeGomez rollup

[bors]

📌 Commit d0a33fb has been approved by GuillaumeGomez

[GuillaumeGomez]

Since it can impact performance, let's not put it into the rollup.

@bors: rollup=iffy

[bors]

⌛ Testing commit d0a33fb with merge c1cb974...

[bors]

☀️ Test successful - checks-actions
Approved by: GuillaumeGomez
Pushing c1cb974 to master...

[rust-timer]

Finished benchmarking commit (c1cb974): comparison url.

Summary: This change led to large relevant regressions 😿 in compiler performance.

• Large regression in instruction counts (up to 3.7% on full builds of externs)

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression

[GuillaumeGomez]

@jsha: It's a big regression for doc build time... Time for optimization I guess. :)