[WIP] Add dfctl CLI and TUI for OTAP Dataflow Engine administration

[lquerel]

Change Summary

Adds dfctl, an admin SDK-based command-line tool for operating local and remote OTAP Dataflow Engines.

The CLI supports engine, group, pipeline, telemetry, rollout, shutdown, reconfiguration, diagnosis, bundle, watch, shell completion, automation friendly output, and an interactive TUI for operational workflows.

What issue does this PR close?

N/A

How are these changes tested?

• cargo xtask check

Are there any user-facing changes?

Yes, the new CLI by itself.

[codecov]

Codecov Report

❌ Patch coverage is 43.20557% with 6031 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.01%. Comparing base (bc4cec8) to head (826ceed).

❌ Your patch check has failed because the patch coverage (43.20%) is below the target coverage (70.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2756      +/-   ##
==========================================
- Coverage   88.13%   86.01%   -2.12%     
==========================================
  Files         645      692      +47     
  Lines      248445   260792   +12347     
==========================================
+ Hits       218956   224322    +5366     
- Misses      28965    35946    +6981     
  Partials      524      524              

Components	Coverage Δ
otap-dataflow	86.97% <43.20%> (-2.75%)	⬇️
query_abstraction	80.61% <ø> (ø)
query_engine	90.75% <ø> (ø)
otel-arrow-go	52.45% <ø> (ø)
quiver	92.25% <ø> (ø)

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