Proposal: Fix Field Artillery Alpha Strike conversion

[Sleet01]

Short form: correct Field Artillery Infantry AS conversion logic (and Field Weapon Infantry weight summation in general) to match current rules, errata, and dev comments.

After protracted pestering of many innocent devs, I believe I have determined that, while MM does the correct thing when converting Infantry with Field Guns, we are not converting Field Artillery (Motorized or Mechanized Infantry units with Arrow IV, Long Tom, Sniper, or Thumper artillery pieces) correctly. This patch proposes to bring this niche unit type in line with the rules, errata, and dev feedback.

According to AS Companion, a unit with artillery weapons should have a normal Damage Line generated from its non-Artillery weapons, and the appropriate ART*-# Special indicating the artillery type and count. As of now, MM doesn't do this; the AS conversion code just assigns "0" to the Damage Line and then applies the ART*-# special.
The AS devs have confirmed that Field Guns (including Artillery Cannons) supersede the damage values derived from Personal and Secondary weapons attached to an infantry unit; we've confirmed that this is working correctly right now.

This patch would skip the Field Gun-specific damage handling if a Conventional Infantry unit both A) has a Field Weapon, and B) that Field Weapon is an Artillery weapon. Otherwise all logic remains the same.

Additionally, this patch will add the tonnage of any ammo (the allowed amount by rules being 1 for Field Artillery, N for N Field Guns) to the weight of the unit; this appears to be skipped in the current calculations.

This will change the PV, Damage Line, and possibly weight of several existing units in MUL.

ID 2131
MUL version:

New version:

ID 2190
MUL version:

New version:

ID 1061
MUL version:

New version:

(Weight inconsistency may be the result of rounding changes or something, but 42 ~= 43 and is closer than the current cached file value, which is 36t)

For reference, also see this AS conversion task list tracking issue:
#3961 (comment)

One of the AS devs confirmed that Artillery is not converted in the same way as Field Guns or Artillery Cannons, saying that the latter two override the Infantry unit's Damage Line but that Artillery weapons don't get an entry on the Damage Line and are instead treated as Specials. (paraphrased)