fix sigv4 canonical request order and revamp test suite

[aajtodd]

Description

Started as an investigation of #4227.

I found that we 1. weren't utilizing most of our test suite (we only used 4 of the test directories from the v4 suite) and 2. that we had a bug in our canonical request implementation where we sort the query keys before encoding instead of after (see https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_sigv-create-signed-request.html#create-canonical-request and the get-vanilla-query-order-encoded test).

This PR does a few things:

1. Imported the CRT test suite and removed the old ones.
   • The previous test suite we were using is the older format that was in use and floating around before CRT updated it. The newer version of this has standardized the file format and includes both header and query versions of each test.
   • We were already using this format for the sigv4a tests so now all of our tests for v4 and v4a use the same format. It also has a few additional tests we didn't have.
   • Using the same format as CRT (and Kotlin) will make it easier to update the test suite or add new tests
2. Updates the test utils to be common across v4 and v4a.
3. Added new test cases we weren't running for both v4 and v4a. Also every test now generally tests both headers and query signature locations (before we were only testing for headers most of the time).
4. Fixed a bug in canonical request implementation where we sort the query keys before encoding instead of after (found by new test and pointed out by engineer on ARC team as well).
5. Migrated a few tests double-encode-path and double-url-encode that we used in several places to the newer format (only for headers not query which was missing).
6. Inlined the iam related test request where it is used
7. Added a new insert_encoded for QueryWriter to append an already encoded key/value pair and skip encoding.

Testing

• During the migration I kept both the old and new test suites around. Then removed the old suite after verifying the tests that utilized the same files still passed on the new test suite.

Checklist

• For changes to the AWS SDK, generated SDK code, or SDK runtime crates, I have created a changelog entry Markdown file in the .changelog directory, specifying "aws-sdk-rust" in the applies_to key.

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[github-actions]

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• AWS SDK (ignoring whitespace)
• No codegen difference in the Client Test
• No codegen difference in the Server Test
• Server Test Python (ignoring whitespace)
• No codegen difference in the Server Test Typescript

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[landonxjames]

Should we add more docs around SIgnableRequest to make it obvious that the uri should be encoded to address the confusion from #4227, or were there going to be more changes for that issue?

[aajtodd]

Should we add more docs around SIgnableRequest to make it obvious that the uri should be encoded to address the confusion from #4227, or were there going to be more changes for that issue?

I wasn't planning on making additional changes but yeah I can add some additional docs to signable request to indicate it should be a encoded URI.

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• Client Test (ignoring whitespace)
• No codegen difference in the Server Test
• Server Test Python (ignoring whitespace)
• No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

[ysaito1001]

Awesome updating the test suite!