JSON backend can be egregiously slow on network filesystems

[klauer]

This pattern was carried forward from the original implementation, just generalized: (I, uh, git blame shows me, but don't blame me 😬 )

Load/yield/save:

happi/happi/backends/json_db.py

Lines 26 to 31 in f8c55b2

	@contextlib.contextmanager
	def _load_and_store_context(backend):
	"""Context manager used to load, and optionally store the JSON database."""
	db = backend._load_or_initialize()
	yield db
	backend.store(db)

Load on every method:

happi/happi/backends/json_db.py

Line 68 in f8c55b2

json = self._load_or_initialize()

This originally was likely an attempt to get around the inability to lock files on the filesystem / concurrent access / etc - all of those things a real database is meant to help with.

What would be a reasonable alternative here - at least keeping the spirit of the original, not just saving on exit?