Updater: change excluded target repos handling

[sale3]

Exclusion of target repositories should not be handled by the updater in update operation. Instead, only clone operation will have the option to exclude certain repo/repos.

• Modify contents of last_validated_commit file in the following way:

1. Put last validated commit of the excluded repo to None
2. Add excluded entry with exclusion filter or excluded repos

Example for excluded archived html repo:

{
    "DCCouncil/law-docs": "80dbb7329f5eca34d04fa65b38a1cf6ced3e7311",
    "DCCouncil/law-xml": "80dbb7329f5eca34d04fa65b38a1cf6ced3e7311",
    "DCCouncil/law-html": None,
    "DCCouncil/law-html-2026": "80dbb7329f5eca34d04fa65b38a1cf6ced3e7311",
    "DCCouncil/law-xml-codified": "80dbb7329f5eca34d04fa65b38a1cf6ced3e7311",
    "DCCouncil/law-static-assets": "80dbb7329f5eca34d04fa65b38a1cf6ced3e7311",
    "DCCouncil/law-rdf": "80dbb7329f5eca34d04fa65b38a1cf6ced3e7311",
    "DCCouncil/law": "80dbb7329f5eca34d04fa65b38a1cf6ced3e7311",
    "last_validated_commit": "80dbb7329f5eca34d04fa65b38a1cf6ced3e7311",
    "exclude_filter": "repo["archived"] is not None"
}

This means that update and reset operation should be extended to check for excluded entries in last validated commit file and use that info to prevent potential failures.

• Remove --exclude-target flag:
  Extend --exclude-filter to handle this functionality instead. If repo['name'] is configured in the filter, the filtering should be done against keys in repositories.json.