Improve performance for mocking interfaces: Cache GetInterfaceMap

[rauhs]

Fixes #1350.

[stakx]

Thanks for suggesting a fix. Let's wait with a possible merge until we've actually looked at the problem first (see my first comment over in the issue.)

[kzu]

Could you please rebase on top of main? There were some fixes there. Thanks!

[rauhs]

Could you please rebase on top of main? There were some fixes there. Thanks!

Sorry for the closing/opening. Had a little struggle with git. We're still using svn at $dayjob.

Should be fine now.

[CLAassistant]

All committers have signed the CLA.

[rauhs]

Any help (i.e. just merge this PR and fix any style changes afterwards) would be highly appreciated. I spend about 5x the time on fighting git than on finding+fixing the actual issue :)

FWIW (and not going to send a PR for this). The following would be good for the editorconfig:

trim_trailing_whitespace = true
csharp_space_before_new_parentheses = false

[rauhs]

@kzu Would love to get this PR merged. Any blockers I need to resolve?

[kzu]

Running the checks now!

[stakx]

Looks good to me.