Ensure all (desired) v1 APIs have v2 equivalent

Nothing in Solr's build system enforced consistency across v1<->v2, so as a result today, many v1 APIs (or API sub-commands) have no v2 counterpart. In some rare cases this was intentional (e.g. /solr/admin/collections?action=MIGRATESTATEFORMAT ), but in most cases it's the result of unintentional omission.

This ticket aims to remedying this, by finding v1 APIs without a v2 counterpart and adding them where desired.