[New Feature] theater-based unit replacement/disabling

[Paladin-Bloodmoon]

First Check

• [X] I added a very descriptive title to this issue.
• [X] I used the GitHub search to find a similar issue and didn't find it.
• [X] I have attached as much information as possible (screenshots, videos, links, etc).

Description

basic concept is that perhaps you want to remove/replace a unit in a specific theater, on all maps in that theater, through rules.ini

Proposed Code (optional)

for rules.ini, the tags would be DisabledInTheater=<the 3 letters of the theater's extension> ;example for disabling in Temperate: DisabledInTheater=tem EnabledInTheater=<the 3 letters of the theater's extension> ;example for enabling in arctic theater: EnabledInTheater=sno

Additional Context

No response