feat(signature-v4-multi-region): add support for sigv4a package

[siddsriv]

Issue

Internal JS-5146

Description

Add support in signature-v4-multi-region for the @smithy/signature-v4a package.
Partner PR: smithy-lang/smithy-typescript#1319

To-Do

• Prepare alias package @aws-sdk/signature-v4a
• Release feat(signature-v4a): create SignatureV4a JavaScript implementation smithy-lang/smithy-typescript#1319 (confirm @smithy/signature-v4a on npm)
• smithy commit update (in a separate PR) for JSv3
  -- codegen sync PR here: chore(clients): update @smithy dependencies #7024
• Re-confirm tests here
• yarn.lock update and commit
• dry-run

Testing

• SignatureV4MultiRegion:

-- Unit tests

 ✓ src/SignatureV4MultiRegion.spec.ts (11)
   ✓ SignatureV4MultiRegion (11)
     ✓ should sign with SigV4 signer
     ✓ should presign with SigV4 signer
     ✓ should presign with SigV4 signer
     ✓ should sign with SigV4a signer if signingRegion is '*'
     ✓ should use SignatureV4a if CrtSignerV4 is not available
     ✓ should throw an error for presignWithCredentials with star region
     ✓ should throw when presigning with signingRegion '*' if CRT is NOT available
     ✓ should throw when presigning with signingRegion '*' in non-node runtime (CRT unavailable)
     ✓ should throw an error if neither CrtSignerV4 nor JsSigV4aSigner is available in node runtime
     ✓ should throw an error if JsSigV4aSigner is not available in non-node runtime
     ✓ should use JsSigV4aSigner in non-node runtime

 Test Files  1 passed (1)
      Tests  11 passed (11)

-- Browser test

 ✓ src/SignatureV4MultiRegion.browser.spec.ts (2)
   ✓ SignatureV4MultiRegion (Browser Bundle SigV4a Test) (2)
     ✓ should use SigV4a for the request when signingRegion is '*' (JS implementation is available in bundle)
     ✓ should throw error when signingRegion is '*' and JS implementation is NOT available (Covered in Unit Tests)

 Test Files  1 passed (1)
      Tests  2 passed (2)

-- E2E tests

✓ src/cloudfront-kvs-sigv4a.e2e.spec.ts (2) 7644ms
 ✓ src/eventbridge-sigv4a-put-api.e2e.spec.ts (2) 18268ms

 Test Files  2 passed (2)
      Tests  4 passed (4)

-- clients/client-s3/test/e2e/s3-mrap-sigv4a.e2e.spec.ts:

 ✓ test/e2e/s3-mrap-sigv4a.e2e.spec.ts (1) 1013ms

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[Lemour-sudo]

Do we have any idea when this can be merged?