Create a cmpRequirements.

[Freagarach]

There are several components using requirements (auras, techs, entities (identity)) it would be nice to have one component handling requirements, such as civ, entity and technology requirements. That would allow to e.g. put formations behind a technology. It would also allow more complex requirements for entities, like we have now for technologies (and auras?).

For the specs, look at the technologies, especially the "all" "any" "none" characteristics.

[Freagarach]

Maybe just a helper for the requirements, such that we don't add a cmp that isn't used after the entity has been created, but we still unify its uses.

[Stan]

Unlikely to get done for A26

[Freagarach]

In 27245:

Add Requirements helper.

Allows more flexibility in e.g. the Identity requirements and unifies the checking of requirements.
One can use the script at ​https://code.wildfiregames.com/P265 to fix templates.

Differential revision: ​https://code.wildfiregames.com/D4514
Comments by: @elexis, @Stan
Fixes #6421