Fix issue 20164: print deprecation if a deprecated module is imported from a local function or a mixin.

[FeepingCreature]

There's two locations where this can come up, so I moved the import deprecation checking code into a helper in dmodule. Not sure if this is the right way to go or if there's a more natural place that's always checked when a module is imported; I couldn't find one offhand.

Ping @Geod24. Hi :)

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	20163	normal	Deprecated import in string mixin does not output diagnostic message
✓	20164	normal	Importing deprecated module at function-local scope does not output diagnostic message

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub fetch digger
dub run digger -- build "master + dmd#10346"

[JinShil]

Please add a DDoc "Params" statement.

[FeepingCreature]

Added.

[Geod24]

Thanks for tackling this! It is lacking tests though.

[FeepingCreature]

Oops! Forgot to git add the test :)

[FeepingCreature]

Added test for 20163 too.

[Geod24]

Last nit: Your commit should reference both issues so that it appears in the changelog.
Otherwise LGTM

[FeepingCreature]

Didn't know you could reference both. Fixed. Ddoc syntax too.

Is it okay for the 20163 test to use the 20164 import?

[FeepingCreature]

Bot didn't pick up the issue number. Trying a different syntax...

edit: Now it got it.

edit: Buildkite failure seems random.