[feature request] allow matched values from source_match_re in target_match

Feature Request
It would be awesome if the target_match and/or target_match_re from inhibit_rules was able to use matched values from source_match_re - this would allow you to inhibit a range of different rules based on some values from the source_match_re.

Looking at the code and docs I couldn't see that this was possible, and I did a quick search of the GitHub issues and couldn't find anything similar.

Example Config

inhibit_rules:
  - source_match_re:
      alertname: 'esx-host-down'
      instance: 'syd-esx-(\d+).mycompany.com'
    target_match:
      alertname: 'vm-not-responding'
      esx_host: 'syd-esx-$1.mycompany.com'

Result
All alerts for vm-not-responding for VMs that have esx_host=syd-esx-01.mycompany.com will be suppressed.

Note
Not sure how this would work in terms of multiple matched values in different keys under source_match_re (do you just use index $1 $2 $3 etc, or do you somehow also include the key from source_match_re? Like $instance.1 (or similar)

Start by tracing how inhibit_rules, source_match_re, target_match, and target_match_re are represented and evaluated. Resolve how captured values and multiple source regular expressions should be referenced, then verify that the example configuration suppresses only matching alerts and that the behavior is documented.