feat: Add out-of-band node metrics (#299)

# Description

This PR adds the following features:

- [x] Add system metrics
- [x] Add process metrics
- [x] Add network metrics
- [x] Add load average metric
- [x] Add database size metric
- [x] Add OS and kernel log entry
- [x] Add Prometheus exporter with endpoint for scraping
- [x] Move integration test utils into a separate module
- [x] Break Homestar process kills into *nix and windows functions
- [x] Switch from `serial` to `file_serial` in integration tests
- [x] Add `taplo` to pre-commit config and nix flake 

## Link to issue

Implements #184

## Type of change

- [x] New feature (non-breaking change that adds functionality)
- [x] Refactor

## Test plan (required)

We have an integration test in `homestar-runtime/tests/metrics.rs`.

---------

Co-authored-by: Zeeshan Lakhani <zeeshan.lakhani@gmail.com>

.gitignore

@@ -23,6 +23,9 @@ private
 homestar-guest-wasm/out
 homestar-wasm/out
 **/fixtures/test_*
+.zed
+result-alejandra
+
 
 # ipfs
 .ipfs

.pre-commit-config.yaml

@@ -35,27 +35,27 @@ repos:
         args: ["--document-private-items"]
         types: [rust]
         pass_filenames: false
+
+  - repo: https://github.com/kamadorueda/alejandra
+    rev: bb7f2ad3f176aa8e9e2944a10061f7989c8fef17  # frozen: 1.3.0
+    hooks:
       - id: alejandra
-        name: alejandra
-        description: Format nix files.
-        entry: alejandra
         files: \.nix$
-        language: system
-      - id: taplo
-        name: taplo
-        description: Format toml files.
-        language: system
-        entry: taplo
-        args: ["fmt"]
-        types:
-          - toml
 
   - repo: https://github.com/DevinR528/cargo-sort
     rev: v1.0.9
     hooks:
       - id: cargo-sort
         args: ["-w"]
 
+  - repo: https://github.com/ComPWA/mirrors-taplo
+    rev: v0.8.1
+    hooks:
+      - id: taplo
+        args: ["fmt"]
+        types:
+          - toml
+
   - repo: https://github.com/compilerla/conventional-pre-commit
     rev: v2.1.1
     hooks: