[Quest] Promotion: Lance Corporal

[KnowOne134]

I affirm:

• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• I have read and understood the Contributing Guide and the Code of Conduct.
• 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?

Adds quest TOAU Promotion: Lance Corporal to game
https://ffxiclopedia.fandom.com/wiki/Promotion:_Lance_Corporal
https://youtu.be/YNGanhF83eY

Steps to test these changes

!completequest 6 90
!completequest 6 91
!setplayervar AssaultPromotion 25
-- Abquhbah: !pos 35.5 -6.6 -58 50
-- Nafiwaa: !pos -74 -6 126 50
-- Mythralline Wellspring 1: !pos -92 -15 -339 51
-- Mythralline Wellspring 2: !pos -218 -15 -388 51
-- Mythralline Wellspring 3: !pos 181 -23 268 51
-- Mythralline Wellspring 4: !pos 259 -23 132 51
-- Mythralline Wellspring 5: !pos 181 -15 373 52