[receiver/googlecloudmonitoring] Add support for delta distributions (#40688)

#### Description

This adds support for converting Google Cloud monitoring delta
distribution metrics to OpenTelemetry histograms.

#### Link to tracking issue

This is related to
#39600,
although it might not be a complete solution, since this only
contributes delta distributions, but not cumulative distributions.

#### Testing

This has been tested extensively with the metric
`run.googleapis.com/request_latencies`.

Here is a comparison of the p95 of that metric directly in Google Cloud
and of the OTel metric as produced by the new code in a third party tool
(Dash0).

<img width="1742" alt="20250612_request_latencies_comparison"
src="https://github.com/user-attachments/assets/dd88d338-3abd-4dfb-a969-72af7c345a5c"
/>

There charts have minor differences which I suspect are introduced by
different interpolation strategies in the two tools (we only have one
datapoint per minute), but besides that, the charts clearly show the
same data -- peaks and valleys are at the same timestamps and the y-axis
values also match.

There are also comprehensive unit tests for the new functionality in
`receiver/googlecloudmonitoringreceiver/internal/metrics_conversion_test.go`.

#### Remarks

Unfortunately I only saw #40216 after I had more or less finished my
implementation here. I realize that this is not ideal, since there are
now two different PRs that attempt to add the same feature. I am not
sure if the author of #40216 is still working on their PR actively. I
think the last status there seems to be that tests are missing. I'm
happy to port over changes from #40216 in case it has things that are
missing here or help porting over changes from here to #40216, if that
helps. That said, this PR has a full set of unit tests and it also has
support for converting the span context exemplar (although that
certainly needs to be double checked, see inline comments).

---------

Co-authored-by: Ben Blackmore <[email protected]>

Author: basti1302

.chloggen/googlecloudmonitoringreceiver-add-support-for-distributions.yaml

@@ -0,0 +1,4 @@
+change_type: enhancement
+component: googlecloudmonitoringreceiver
+note: Add support for converting Google Cloud monitoring delta distribution metrics to OpenTelemetry histograms.
+issues: [39600]

receiver/googlecloudmonitoringreceiver/go.mod

@@ -3,6 +3,8 @@ module github.com/open-telemetry/opentelemetry-collector-contrib/receiver/google
 go 1.23.0
 
 require (
+	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/golden v0.128.0
+	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatatest v0.128.0
 	github.com/stretchr/testify v1.10.0
 	go.opentelemetry.io/collector/component v1.34.1-0.20250610090210-188191247685
 	go.opentelemetry.io/collector/component/componenttest v0.128.1-0.20250610090210-188191247685
@@ -22,11 +24,13 @@ require (
 	cloud.google.com/go/auth v0.16.1 // indirect
 	cloud.google.com/go/auth/oauth2adapt v0.2.8 // indirect
 	cloud.google.com/go/compute/metadata v0.7.0 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/gobwas/glob v0.2.3 // indirect
 	github.com/google/s2a-go v0.1.9 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.6 // indirect
 	github.com/googleapis/gax-go/v2 v2.14.2 // indirect
 	github.com/hashicorp/go-version v1.7.0 // indirect
+	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatautil v0.128.0 // indirect
 	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
 	go.opentelemetry.io/collector/consumer/consumererror v0.128.1-0.20250610090210-188191247685 // indirect
 	go.opentelemetry.io/collector/consumer/xconsumer v0.128.1-0.20250610090210-188191247685 // indirect
@@ -79,3 +83,9 @@ require (
 	google.golang.org/protobuf v1.36.6
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatatest => ../../pkg/pdatatest
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatautil => ../../pkg/pdatautil
+
+replace github.com/open-telemetry/opentelemetry-collector-contrib/pkg/golden => ../../pkg/golden