[Feature Request] az pipelines runs artifact download - add capability to download individual files matching a pattern

**Is your feature request related to a problem? Please describe.**
Currently, "az pipelines runs artifact download --artifact-name [artifact-name]" downloads all files in [artifact-name].

If there is a large number / size of files in [artifact-name], and we only need one or some of them, this can be very time and bandwidth consuming.

**Describe the solution you'd like**
Capability to only download files that match a specified pattern,

For example (adding a --pattern argument):
az pipelines runs artifact download --artifact-name [artifact-name] --path [output-path] --run-id [run-id] --pattern [pattern]

I have a proposed solution in https://github.com/mpeck12/azure-devops-cli-extension/commit/37d73798f420753759a2c8637c456efd95085adc

Start at the implementation entry point for `az pipelines runs artifact download` and review the proposed solution in commit 37d73798f420753759a2c8637c456efd95085adc. Verify how the new pattern argument should select files from an artifact, then confirm that matching files alone are downloaded to the requested output path.

Written by the indexing model from the issue text.