failing to start sidecar gets real noisy in sentry

[jlrobins]

throw new Error(getHandlePromise(${callnum}): failed to start sidecar);

when it happens the first time for user, for whatever / currently unknown reason, will end up happening A LOT.

Add a latch in sidecarManager.ts that gets set when this happens the first time, to then prevent even trying to start sidecar (until extension reset / restart).