Enable clippy::panic in const contexts

[YohDeadfall]

Fixes #15564.

changelog: [cargo::panic]: Enabled to run in const contexts

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[samueltardieu]

It should still probably not trigger in always const context, evaluated at compile-time.

[github-actions]

Lintcheck changes for e54afd3

Lint	Added	Removed	Changed
clippy::panic	14	0	0

This comment will be updated if you push new changes

[samueltardieu]

(the intent of #8358 seem to be about always const contexts anyway)

You can use clippy_utils::is_inside_always_const_context() for this.

[samueltardieu]

Can you please squash the commits?

r? samueltardieu

[YohDeadfall]

Squashed. Thank you!

[samueltardieu]

Thanks.