Prometheus: Introduce prometheus backend library (#83952)

* Move files to prometheus-library

* refactor core prometheus to use prometheus-library

* modify client transport options

* mock

* have a type

* import aliases

* rename

* call the right method

* remove unrelated test from the library

* update codeowners

* go work sync

* update go.work.sum

* make swagger-clean && make openapi3-gen

* add promlib to makefile

* remove clilogger

* Export the function

* update unit test

* add prometheus_test.go

* fix mock type

* use mapUtil from grafana-plugin-sdk-go

pkg/promlib/testdata/exemplar.query.json

@@ -0,0 +1,8 @@
+{
+  "RefId": "A",
+  "ExemplarQuery": true,
+  "Start": 1654086510,
+  "End": 1654086810,
+  "Step": 15,
+  "Expr": "histogram_quantile(0.99, sum(rate(traces_spanmetrics_duration_seconds_bucket[15s])) by (le))"
+}