export prom metrics from the printer

[paultag]

more work to be done, but this will poll the implemented machine(s) to export prom metrics about the health and status of the connected machine(s).

This has a ways to go, but it's a start. Going to try and build out good coverage for my printer and then see if I can sprint on the X1 next.

# HELP extruder_temperature_celsius Last temp of the extruder.
# TYPE extruder_temperature_celsius gauge
# UNIT extruder_temperature_celsius celsius
extruder_temperature_celsius{id="neptune"} 219.87
# HELP extruder_temperature_target_celsius Target temp of the extruder.
# TYPE extruder_temperature_target_celsius gauge
# UNIT extruder_temperature_target_celsius celsius
extruder_temperature_target_celsius{id="neptune"} 220.0
# HELP bed_temperature_celsius Last temp of the bed.
# TYPE bead_temperature_celsius gauge
# UNIT bead_temperature_celsius celsius
bed_temperature_celsius{id="neptune"} 60.2
# HELP bed_temperature_target_celsius Target temp of the bed.
# TYPE bed_temperature_target_celsius gauge
# UNIT bed_temperature_target_celsius celsius
bed_temperature_target_celsius{id="neptune"} 60.0

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 10.28037% with 96 lines in your changes missing coverage. Please review.

Project coverage is 23.30%. Comparing base (6d2dcae) to head (217462b). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/bin/machine-api/cmd_serve.rs	0.00%	68 Missing :warning:
src/server/endpoints.rs	7.69%	12 Missing :warning:
src/server/raw.rs	0.00%	7 Missing :warning:
src/server/mod.rs	53.84%	6 Missing :warning:
src/moonraker/mod.rs	0.00%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #121 +/- ## ========================================== - Coverage 23.89% 23.30% -0.59% ========================================== Files 47 48 +1 Lines 2507 2609 +102 ========================================== + Hits 599 608 +9 - Misses 1908 2001 +93 ``` | [Flag](https://app.codecov.io/gh/KittyCAD/machine-api/pull/121/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=KittyCAD) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/KittyCAD/machine-api/pull/121/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=KittyCAD) | `23.30% <10.28%> (-0.59%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=KittyCAD#carryforward-flags-in-the-pull-request-comment) to find out more.

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[paultag]

todo: remove autometrics

[paultag]

autometrics has been excised; will land when it's green - working locally against my printer