[stdlib] Rename Slab to InlineArray

[Azoy]

In accordance with the evolution acceptance notes here: https://forums.swift.org/t/accepted-with-modifications-se-0453-inlinearray-formerly-vector-a-fixed-size-array/77678/29

[Azoy]

@swift-ci please test

[DougGregor]

Thanks!

[etcwilde]

Approving changes to the new build system.

[Azoy]

@swift-ci please smoke test

[Azoy]

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[glessard]

@swift-ci please smoke test

[glessard]

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[glessard]

Looks like Sema/typo_correction.swift's behaviour reverted to what it was before you changed it in 4c5a13a:

-  let plop = 4 // expected-note {{'plop' declared here}}
+  let plop = 4 // expected-note {{did you mean 'plop'?}}

[glessard]

@swift-ci please smoke test