refactor: error handling with thiserror, anyhow for runtime only

[zeeshanlakhani]

Closes #62

This PR includes:

• flake commands for helpful shortcuts
• move to cargo nextest
• worker tests
• addition of workspace macros bail and ensure for internal error handling
• moves general workflow structure to homestar-core, with generic handling, and allows for further building blocks

[codecov]

Codecov Report

Merging #139 (fce6ad5) into main (ec5dd3a) will decrease coverage by 0.48%.
The diff coverage is 39.20%.

@@            Coverage Diff             @@
##             main     #139      +/-   ##
==========================================
- Coverage   49.47%   48.99%   -0.48%     
==========================================
  Files          42       46       +4     
  Lines        2001     2092      +91     
  Branches      516      521       +5     
==========================================
+ Hits          990     1025      +35     
- Misses        693      745      +52     
- Partials      318      322       +4     

Impacted Files	Coverage Δ
homestar-core/src/lib.rs	100.00% <ø> (ø)
homestar-core/src/workflow/ability.rs	80.00% <ø> (ø)
homestar-core/src/workflow/config.rs	60.52% <ø> (ø)
homestar-core/src/workflow/invocation.rs	65.21% <0.00%> (ø)
homestar-core/src/workflow/issuer.rs	0.00% <ø> (ø)
homestar-core/src/workflow/nonce.rs	31.03% <0.00%> (-2.30%)	⬇️
homestar-core/src/workflow/prf.rs	53.84% <ø> (ø)
homestar-runtime/src/lib.rs	100.00% <ø> (ø)
homestar-runtime/src/main.rs	4.34% <ø> (ø)
homestar-runtime/src/worker.rs	43.90% <0.00%> (-0.88%)	⬇️
... and 21 more