Split "semantic" tests out to a separate package

See merge request !45

Release 0.4.0.1

See merge request !44

Dependency update

See merge request !43

Release 0.4.0.0

See merge request !42

Implement write enabler and mutable reads for the Filesystem backend

See merge request !41

Make the write enabler tests pass

See merge request !40

The "False" response is for failed test vectors.

Co-Authored-By:  <meejah@meejah.ca>

Make a "write enabler secret" available to the ReadTestWrite endpoint

Closes #28

See merge request !39

To avoid making each backend responsible for picking out the right secret