Fix 6240: era-illegal asf bombs [Note: breaks MHQ]

[Sleet01]

Fixes the long-standing issue where automatically-generated ASF munitions ignore era restrictions, leading to e.g. early CI enemy forces with Thunder bombs.
The implementation re-uses existing era legality checks from the non-ASF munitions generation code.
Auto-generated ASF munitions should now all be restricted to era-appropriate options in both MM and MHQ.

As a sop to Princess, however, this also implements Rocket Launcher (Prototype), or RL-P, bomb pods.
This will allow Clan ASFs to be equipped with RL-P pods through 2823, and IS ASFs from the Early Spaceflight period on.

Testing:

• Ran all 3 suites' unit tests (This breaks MHQ, requiring a separate patch there)
• Added unit tests to confirm era-appropriate munition selection for IS and Clan units.

NOTE: MegaMek/mekhq#5337 needs to be pulled in close conjunction with this PR.

Close #6240

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 29.03%. Comparing base (2e45dc0) to head (5ad56d7).
Report is 9 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6254      +/-   ##
============================================
+ Coverage     28.99%   29.03%   +0.04%     
- Complexity    13982    14008      +26     
============================================
  Files          2652     2653       +1     
  Lines        268296   268377      +81     
  Branches      47764    47770       +6     
============================================
+ Hits          77799    77934     +135     
+ Misses       186615   186543      -72     
- Partials       3882     3900      +18     

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[IllianiCBT]

I am always nervous reviewing MM content, but this looks fine to my eyes. I would prefer a second opinion before it gets merged.