Add shared workflows

[h4sh3d]

Use workflows described in monero-rs/workflows repo.

[codecov]

Codecov Report

Merging #14 (157489f) into main (dc44b61) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #14   +/-   ##
=======================================
  Coverage   94.57%   94.57%           
=======================================
  Files           1        1           
  Lines         516      516           
=======================================
  Hits          488      488           
  Misses         28       28           

---

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 dc44b61...157489f. Read the comment docs.