Fix #19071: ensure `completion_item_hash` serializes items uniquely

Previously it may have been possible for different completion items to
produce colliding hashes, not because of the hash but because of how
the items were serialized into byte streams for hashing. See #19071
for details.

The chances of that happening were low, if it was actually possible at
all. Nevertheless, this commit ensures that it definitely can't happen.

This commit uses a handful of techniques used to fix this, but they all
boil down to "ensure this could be re-parsed". If it's possible to parse
to recreate the original item, then by construction there is no chance
of two different items getting serialized to identical byte streams.

0 files changed, 0 insertions, 0 deletions