Support glob/regex patterns for self hosted runner labels configuration

[kishaningithub]

Context

To add self hosted runners to the list i am doing something like

self-hosted-runner:
    labels:
      - private-runner-label1
      - private-runner-label2

but the problem the above way of configuration is not ideal if the label contains a dynamic elements, For example

self-hosted-runner:
    labels:
      - INSTANCE_TYPE=m6a.large # Yes this is a label :-)  

In the above the value of the INSTANCE_TYPE can be anything (t3.large, m2.large etc etc) and they are all valid github runner labels

Proposal

It would be great if this configuration can be made into a pattern like

self-hosted-runner:
    labels:
      - INSTANCE_TYPE=*  # The * matches everything  

This way i don't have to specify each and every label

[rhysd]

Closing as #378. Now glob pattern is supported.