Add ability to search only for non-inherited tags

[xxiii23]

Referencing the issue described in #1055, #1064:

We'd intentionally like the ability to search only non-inherited tags.

Example:

"#NAT" returns many, many entries, while "##NAT", or perhaps "%NAT" (I arbitrarily picked a different prefix for this example), would return only the parent prefix(s).

Explanation / justification:

We are currently going through and adding a distinctive word to the description of the parent networks that we want to find without their children as a workaround, but this has a "human error / consistency / memory / whats-an-appropriate-word / 2-places-instead-of-one" factor, whereas the ability to search only non-inherited tags would automatically give us this ability, for any tag.

We have a number of cases where a parent prefix has a large number of child prefixes (which themselves each have a large number of child prefixes), and situations where we'd like to find only the parent(s) with a given tag and then drill down from there.

(And / or alternatively we'd like the ability have tags that don't get inherited (in addition to still having the inheritable ones; but I think the direct-only search ability would still be useful even if this were the case)).