fab set in build update hld pipeline should set image tag in different config file

[bnookala]

Describe the bug:

As filed by this user issue: #1060, the build-update-hld pipeline will change the same common.yaml file for multiple service builds (either mono-repository or not mono repository)

To Reproduce:

1. have two services set up, building and configuring the same HLD repository
2. commit to one service, note the PR against the HLD - do not merge it.
3. commit to second service, second PR is generated against HLD
4. merge the first PR to the HLD
5. the second PR will not be able to be merged as there will be a conflict

Expected behavior:

both PRs should be able to be merged

Additional context:

this is likely happening as all PRs against the HLD update the same file. As there exists multiple places for configuring image tag etc, we should be able to set the configuration further down in the HLD - not just in the root level config/common.yaml - this should prevent any conflicts from two completely separate services updating the same configuration file.

this line is where we set fab configuration :https://github.com/CatalystCode/spk/blob/master/src/lib/fileutils.ts#L301

Does this require updates to documentation?:

yes