discard stale completion requests

Completion requests are computed asynchronously to avoid common micro
freezes while editing. This means that once a completion request
completes, the state of the editor might have changed. Currently,
there is a check to ensure we are still in insert mode. However,
we also need to ensure that the view and document hasn't changed
to avoid accidentally using a savepoint with the wrong view/document.

Furthermore, the editor might request a new completion while the
previous completion request hasn't complemented yet. This can
lead to weird flickering or an outdated completion request replacing
a newer completion that has already completed (the LSP server
is not required to process completion requests in order). This change
also needed to ensure determinism/linear ordering so that completion
popup always correspond to the last completion request.

0 files changed, 0 insertions, 0 deletions