lsp should prioritize .flowconfig lazy_mode
lsp should prioritize .flowconfig lazy_mode

Summary:
Nuclide runs `flow lsp --lazy-mode ide`. However, if the `.flowconfig` has `lazy_mode=watchman`, we want to use that.

Usually, CLI flags override the `.flowconfig`. But in this particular case we want this to be a fallback for when the `.flowconfig` doesn't specify a lazy mode.

Reviewed By: ljw1004

Differential Revision: D14859836

fbshipit-source-id: f493f80dfaa88218901a45a2bc96101ef28870d0

samwgoldman/flow,gabelevi/flow,samwgoldman/flow,facebook/flow,gabelevi/flow,gabelevi/flow,facebook/flow,samwgoldman/flow,gabelevi/flow,mroch/flow,samwgoldman/flow,facebook/flow,mroch/flow,mroch/flow,samwgoldman/flow,gabelevi/flow,facebook/flow,mroch/flow,facebook/flow,mroch/flow,mroch/flow,gabelevi/flow,mroch/flow,samwgoldman/flow,facebook/flow,facebook/flow,samwgoldman/flow,gabelevi/flow