feat: MongoDB support

[DRK3]

• Added support for MongoDB as a backing storage provider.
• Refactored some code which will allow support for other storage implementations to be added more easily in the future.
• As a result of this refactoring, the in-memory storage provider can now be used for vault encrypted indexes + querying.
• Added a TODO marker to the OpenAPI demo script for an existing issue.

Signed-off-by: Derek Trider Derek.Trider@securekey.com

closes #222 closes #135

[codecov[bot]]

Codecov Report

Merging #221 (05ba5e8) into main (f9bd7e7) will decrease coverage by 0.34%. The diff coverage is 89.61%.

@@            Coverage Diff             @@
##             main     #221      +/-   ##
==========================================
- Coverage   86.68%   86.33%   -0.35%     
==========================================
  Files          14       13       -1     
  Lines        1847     1793      -54     
==========================================
- Hits         1601     1548      -53     
- Misses        150      151       +1     
+ Partials       96       94       -2     

Impacted Files	Coverage Δ
pkg/auth/zcapld/service.go	83.33% <ø> (ø)
pkg/restapi/operation/operations.go	86.04% <ø> (ø)
cmd/edv-rest/startcmd/start.go	80.56% <52.63%> (-1.87%)	:arrow_down:
pkg/edvprovider/edvprovider.go	91.82% <91.82%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update f9bd7e7...05ba5e8. Read the comment docs.