Auto merge of #18247 - jhgg:lsp/fix-something-to-resolve, r=Veykril

lsp: fix completion_item something_to_resolve not being a latch to true

while looking at #18245 i noticed that `something_to_resolve` could technically flap between true -> false if some subsequent fields that were requested to be resolved were empty.

this fixes that by using `|=` instead of `=` when assigning to `something_to_resolve` which will prevent it from going back to false once set.

although some cases it's simply assigning to `true` i opted to continue to use `|=` there for uniformity sake. but happy to change those back to `=`'s.

cc `@SomeoneToIgnore`

Author: bors