CustomSpawnRequest2 with arbitrary user data inserted into NpcData

[ryo0ka]

Changes

Added a new parameter string context to MESApi.CustomSpawnRequest(), which is inserted into NpcData.Context of spawned NPC grids.

Background

I wasn't able to reliably track each spawn request's corresponding grid when I spawn a single spawn group multiple times simultaneously in close proximity. I guess that kind of usage wasn't expected. This PR would allow me to retrieve an identifier of each spawn request upon a callback of RegisterSuccessfulSpawnAction() or a modded block's init function.

For an added value, the string data can carry around XML which may be useful to pass arbitrary data to grids.

Implementation notes

For backward compatibility, I didn't get to change the signature of CustomSpawnRequest() but added an override, with a single parameter args, which is of new type CustomSpawnRequestArgs. Internally, API will pass around a string -> object dictionary that is converted to/from this class.

This approach also allows you to safely add other parameters to the function in future updates.

Tests conducted prior to PR

• ran new CustomSpawnRequest() with context data and confirmed working as expected.
• ran the original CustomSpawnRequest() and confirmed that the behavior hasn't changed.
• ran general MES spawner via /MES.SSCS and natural spawns and confirmed the behavior hasn't changed.