Stop filtering out diagnostics with invalid locations in the editor
diagnostic consumer, and instead capture them separately so that we can
include them in did-compile notifications.
rdar://39225000
The only interesting change here is that I stopped filtering out
non-note diagnostics from outside the "inputs". This matches better how
code-completion gets inputs, and shouldn't hurt anything else since only
the tracing code will look at diagnostics that aren't in specific
buffers anyway.
rdar://38438512
When enabled, send a notification before/after every "compilation",
which for now means `performSema`. This piggy-backs and modifies some
existing code that we had for "tracing" operations in sourcekitd that
unfortunately was untested. At least now some of the basic parts are
tested via the new notifications.
Part of rdar://38438512