TrustStore: Add metrics

[oncilla]

This pull request adds the following metrics to the trust store:

 # HELP truststore_created_signatures_total Number of signatures created with a signer backed by the trust store
 # TYPE truststore_created_signatures_total counter
 truststore_created_signatures_total{result="ok_success"} 531
 # HELP truststore_db_queries_total Total queries to the database
 # TYPE truststore_db_queries_total counter
 truststore_db_queries_total{driver="sqlite",operation="chain_exists",result="ok_success"} 7
 truststore_db_queries_total{driver="sqlite",operation="get_issuing_key_info",result="ok_success"} 734
 # HELP truststore_generated_signers_total Number of generated signers backed by the trust store
 # TYPE truststore_generated_signers_total counter
 truststore_generated_signers_total{result="ok_success"} 5
 # HELP truststore_insertions_total Number of trust material insertions handled by the trust store
 # TYPE truststore_insertions_total counter
 truststore_insertions_total{result="ok_exists",type="chain"} 1
 truststore_insertions_total{result="ok_exists",type="trc"} 2
 truststore_insertions_total{result="ok_inserted",type="chain"} 6
 # HELP truststore_lookups_total Number of trust material lookups handled by the trust store
 # TYPE truststore_lookups_total counter
 truststore_lookups_total{result="ok_success",trigger="application",type="chain"} 5
 truststore_lookups_total{result="ok_success",trigger="application",type="trc"} 5
 truststore_lookups_total{result="ok_success",trigger="chain_request",type="chain"} 20
 truststore_lookups_total{result="ok_success",trigger="signature_verification",type="as_key"} 362
 # HELP truststore_received_requests_total Number of RPCs served by the trust store
 # TYPE truststore_received_requests_total counter
 truststore_received_requests_total{client="as_local",req_type="chain_request",result="ok_success"} 6
 truststore_received_requests_total{client="isd_local",req_type="chain_request",result="ok_success"} 9
 truststore_received_requests_total{client="isd_remote",req_type="chain_request",result="ok_success"} 5
 # HELP truststore_sent_requests_total Number of crypto fetches started by the trust store
 # TYPE truststore_sent_requests_total counter
 truststore_sent_requests_total{peer="isd_local",result="ok_success",trigger="signature_verification",type="chain_request"} 3
 truststore_sent_requests_total{peer="isd_remote",result="ok_success",trigger="signature_verification",type="chain_request"} 3
 # HELP truststore_trc_inspections_total Number of TRC inspections handled by the trust store
 # TYPE truststore_trc_inspections_total counter
 truststore_trc_inspections_total{result="ok_success",type="by_attributes"} 1
 truststore_trc_inspections_total{result="ok_success",type="has_attributes"} 80
 # HELP truststore_verified_signatures_total Number of signatures verifications backed by the trust store
 # TYPE truststore_verified_signatures_total counter
 truststore_verified_signatures_total{result="ok_success"} 362

fixes #3488

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This change is 

[lukedirtwalker]

Reviewed 37 of 37 files at r1.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @oncilla)

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go/lib/infra/modules/trust/verifier.go, line 98 at r1 (raw file):

	if err != nil {
		metrics.Verifier.Verify(l.WithResult(metrics.ErrParse)).Inc()
		return err

does this error also need ErrValidation wrap?

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go/lib/infra/modules/trust/internal/metrics/handler.go, line 55 at r1 (raw file):

func newHandler() handler {
	return handler{
		requests: *prom.NewCounterVecWithLabels(Namespace, "", "received_requests_total",

I think it's better to leave the name as is, if it already is used somewhere this will only break it, if we don't change it, stuff will not break and it is also not wrong.

[oncilla]

Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @lukedirtwalker)

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go/lib/infra/modules/trust/verifier.go, line 98 at r1 (raw file):

Previously, lukedirtwalker (Lukas Vogel) wrote…

does this error also need ErrValidation wrap?

Done.

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go/lib/infra/modules/trust/internal/metrics/handler.go, line 55 at r1 (raw file):

Previously, lukedirtwalker (Lukas Vogel) wrote…

I think it's better to leave the name as is, if it already is used somewhere this will only break it, if we don't change it, stuff will not break and it is also not wrong.

Done.

[lukedirtwalker]

Reviewed 13 of 13 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved