Update SSH keys delete script

What does this MR do?

While updating the script to account for !30575 (merged) I stumbled across a few more changes that could be made.

• Defaults to deleting keys with new title prefix 'E2E test key:'
• Allows specifying the part of the title to match
• Allows a dry run that lists keys without deleting them
• Allows deletion only if keys were created before a given date
• Handles pagination
• Deletes keys for the user who owns the access token supplied. This lets us use the script in prod or other environments where we don't have an admin account

Should wait until !30575 (merged) is merged before running the script with defaults because it expects new keys to have the title set in that MR. Might as well wait until the new keys start showing up before running the script again to delete all the old ones.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team