Fix QualityBuilder NRE when its designator field became non-static

[pkp24]

Code by claude code, multiple people who use MPCompat have said this change seems to work fine. I haven't personally tested it since I don't play multiplayer.

MpCompatLoader logged "Exception loading hatti.qualitybuilder: System.NullReferenceException" on startup with QualityBuilder installed.

Root cause: the patch resolved the skilled-builder designator's right-click "set min quality" lambda by hard-coding the compiler-generated closure type name "QualityBuilder._Designator_SkilledBuilder+<>c". That cached <>c closure only exists while the lambda captures nothing. A recent QualityBuilder change made the designator's quality field (curQualityCat) a per-instance field instead of static, so the lambda now captures this and the compiler emits it as an instance method on the designator itself -- the <>c type no longer exists. AccessTools.TypeByName then returned null, and GetFirstMethodBySignature(null, ...) dereferenced it, throwing the NRE and aborting the whole compat class (so ToggleSkilled and the gizmo menu weren't synced either).

Fix: sync the designator's state instead of the choice-setting lambda. Register a SyncWorker for _Designator_SkilledBuilder that serializes curQualityCat, so MP replays each designation with the chosen quality and every client builds it at the same quality -- the same idiom other modded designators use (e.g. Dubs Bad Hygiene). This is also the only mechanism that still carries the quality after the refactor: the old approach synced the pick into a static field, but curQualityCat is now per-instance, so syncing the pick alone would no longer reach the designation (a latent desync even once the NRE is fixed). Each player's own menu pick stays local to their designator; the applied quality is what syncs.

Also null-guard the three TypeByName lookups so a future internal rename in QualityBuilder degrades to a warning instead of taking down the compat class.

[Grntrenchman]

I can confirm that this commit fixes MP Compat for Qualitybuilder Unofficial 1.6 7/10 update, which otherwise does not work properly and throws NRE at launch.