[module] [lua] Pet EXP Module

[KiplingFFXI]

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• I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

This PR adds a custom module that cuts the EXP awarded for killing another monster's pet when the killing party has more than 3 members. Parties of 3 or fewer are untouched. At 4 members pets give 30% of their normal value, (70% penalty) at 5 members 20% (80% penalty), and at 6 or more 10% (90% penalty).

"Pet" means a mob with an actual master link (everything wired up through xi.pet.setMobPet), so beastmen jug pets, wyverns, avatars, and elementals are included. Adds spawned as loose helpers through callPets have no master and are not affected.
Player-owned pets are excluded. Charmed mobs and jug pets have a player master, and the module checks that the master is a mob before touching anything.

Also, if you engage a pet with 4-6 in your party and then people drop, the penalty is still not avoided. It is calculated base don the party size you had on engage.

Steps to test these changes

Load the module. Kills pets as a party of 3 and see its normal. Kill as a party of 4-6 and see your EXP is severely reduced.