[feature] Initial Prometheus metrics implementation (#2334)

* feat: Initial OTEL metrics

* docs: add metrics documentation

* fix: metrics endpoint conditional check

* feat: metrics endpoint basic auth

* fix: make metrics-auth-enabled default false

* fix: go fmt helpers.gen.go

* fix: add metric-related env vars to envparsing.sh

* fix: metrics docs

* fix: metrics related stuff in envparsing.sh

* fix: metrics docs

* chore: metrics docs wording

* fix: metrics stuff in envparsing?

* bump otel versions

---------

Co-authored-by: Tsuribori <user@acertaindebian>
Co-authored-by: Tsuribori <none@example.org>
Co-authored-by: tsmethurst <tobi.smethurst@protonmail.com>

vendor/github.com/prometheus/procfs/.golangci.yml

@@ -0,0 +1,15 @@
+---
+linters:
+  enable:
+  - godot
+  - misspell
+  - revive
+
+linter-settings:
+  godot:
+    capital: true
+    exclude:
+    # Ignore "See: URL"
+    - 'See:'
+  misspell:
+    locale: US