[feature] gRPC

[KCarretto]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Changes:

• Refactor tavern http and Auth code
• Define a c2.proto spec for agent communication
• Implement a http/2 gRPC server hosted on the same server as the tavern GraphQL api
• Generate Rust gRPC client code and update imix to use it as the primary mechanism for callbacks

What’s left:

• Follow up with tonic folks to get the path issue resolved (URI path is not respected in Endpoint hyperium/tonic#1314)
• Fix imix tests
• Write more server side tests
• Identify things that probably broke and fix them

Which issue(s) this PR fixes:

Fixes #331

[hulto]

Can we move this to the parent workspace.
If other parts of realm use it in the future would be nice to continue our standard of using one version of a dep across the project.

[KCarretto]

idk how to add build dependencies there, no existing section for them

[hulto]

Should be able to add:

[workspace.build-dependencies]
tonic-build = "0.10"

to between dependencies and profile.

[KCarretto]

Doesn't work like that, would require us to add it to the workspace dependencies:

Caused by:
  failed to load manifest for dependency `c2`

Caused by:
  failed to parse manifest at `/workspaces/realm/implants/lib/c2/Cargo.toml`

Caused by:
  error inheriting `tonic-build` from workspace root manifest's `workspace.dependencies.tonic-build`

Caused by:
  `dependency.tonic-build` was not found in `workspace.dependencies`

[KCarretto]

Added them to the workspace dependencies I guess /shrug

[codecov]

Codecov Report

Attention: 485 lines in your changes are missing coverage. Please review.

Comparison is base (6cd9f5e) 75.35% compared to head (e4570d1) 68.49%.

Files	Patch %	Lines
implants/imix/src/main.rs	0.87%	227 Missing ⚠️
implants/lib/c2/src/c2.rs	0.00%	130 Missing ⚠️
tavern/internal/c2/server.go	42.03%	82 Missing and 9 partials ⚠️
implants/lib/eldritch/src/lib.rs	86.44%	16 Missing ⚠️
tavern/app.go	71.92%	13 Missing and 3 partials ⚠️
tavern/internal/c2/rollback.go	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #380      +/-   ##
==========================================
- Coverage   75.35%   68.49%   -6.87%     
==========================================
  Files         107      106       -1     
  Lines        7255     7122     -133     
==========================================
- Hits         5467     4878     -589     
- Misses       1690     2136     +446     
- Partials       98      108      +10     

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[hulto]

Second look over couple more comments.