fix: improve tag parsing performance for list input

[hawflau]

Which issue(s) does this change fix?

#6657

Why is this change necessary?

When tags are provided as list via samconfig.toml and certain tag values contain space, performance could be poor as tag parsing will have to do regex parsing with a complex regex pattern.

How does it address the issue?

• For list input (via samconfig.toml), just convert the list to tuple so each tag is handled separately

What side effects does this change have?

No

Mandatory Checklist

PRs will only be reviewed after checklist is complete

• Add input/output type hints to new functions/methods
• Write design document if needed (Do I need to write a design document?)
• Write/update unit tests
• Write/update integration tests
• Write/update functional tests if needed
• make pr passes
• make update-reproducible-reqs if dependencies were changed
• Write documentation

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.