Give air(ship)base templates SAMs after invention or 1950+

[pratapon51]

Right now, airbases (and other coastal defenses besides Missile Batteries, really) are highly vulnerable to jet era naval aviation because they don't get any SAMs. They likely should! It becomes trivial to suppress them and destroy their precious airplanes.

Land installations appear to update at specific game-years, so I think an easy stopgap solution would be to slap on an MSAM and LSAM on the 1970 airbase template used 1950 onwards. Handwave it, if the tech isn't available yet, as Army-Airforce tech or teething issues with the navalized version.

[brygun]

There is a fair bit of "what if" available for Airships.

Certainly SAM on air bases would make sense.