Sigv4 gem updates: SRA Identity + backports

[alextwoods]

Description of changes:

Removes options for credential_providers and instead requires users to provide credentials when calling any of the signing methods. This removes the multiple different ways to configure credentials when signing and uses the interface to enforce best practices around credential refreshing.

Adds support for passing a request object (eg: a Hearth::HTTP::Request) and supports using either url or uri from the request (url takes precedence if both are provided).

Updates other parameter names (uri_escape_path and normalize_path) to match CRT names.

Backports changes from v3 sigv4 gem:

• Minimum of expiration time and expires_in for presigned urls aws/aws-sdk-ruby#2872
• Fix space trimming of header values in sigv4 signer aws/aws-sdk-ruby#2760
• (Static Stability) use provided expires_in in presigned url when credentials are expired aws/aws-sdk-ruby#2933

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.