Expose --delay and --max-attempts for wait commands (#1295)

[minjcho]

Issue #, if available:
Fixes #1295

Description of changes:

• Add --delay and --max-attempts arguments to waiter commands.
• Pass the provided values through WaiterConfig when invoking waiter.wait().
• Update waiter help text to document the new options.
• Add unit coverage for argument parsing, help output, and waiter config injection.

Description of tests:

• Added unit tests covering argument parsing, help output, and waiter config injection.
• Ran python -m pytest tests/unit/customizations/test_waiters.py -q — all pass.
• Succeeded manual testing described below.

Manual testing:

Verified the new flags appear in the generated help output:

aws ec2 wait instance-running help

I confirmed that [--delay <value>] and [--max-attempts <value>] are listed in the synopsis and documented in the options section.

Then I ran:

aws ec2 wait instance-running --instance-ids <YOUR_INSTANCE_ID> --delay 5 --max-attempts 10

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