feat: add support for configuring scope info metric attributes for the Prometheus exporter and refactor conversion to Prometheus metrics

[herin049]

Description

Adds support for configuring scope attributes for the Prometheus exporter in accordance to the Prometheus spec and refactor conversion to Prometheus metrics.

Fixes #5112

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

uv run tox -e py314-test-opentelemetry-exporter-prometheus

Does This PR Require a Contrib Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[MikeGoldsmith]

This looks like it's on the right path. A few things to note:

1. _SCOPE_ATTR_CONFLICT_NAMES is defined but never used — we should either use it to explicitly filter conflicting scope attributes or remove it.

2. PR description looks copy-pasted from #5122 — says "Resource metrics as Metric attributes" but this is about scope info.

3. Merge conflict concern — this, #5122, #5118, and #5117 all modify PrometheusMetricReader and _translate_to_prometheus. This is going to conflict with them, we need to coordinate what should be done in order or we'll be bumping into each other with rebases.

4. nit: the nesting depth in _translate_to_prometheus is getting deep — might be worth extracting the per-metric logic into a helper in a follow-up.

[herin049]

This looks like it's on the right path. A few things to note:

1. _SCOPE_ATTR_CONFLICT_NAMES is defined but never used — we should either use it to explicitly filter conflicting scope attributes or remove it.
2. PR description looks copy-pasted from feat: add support for Resource attributes configuration for Prometheus exporter #5122 — says "Resource metrics as Metric attributes" but this is about scope info.
3. Merge conflict concern — this, feat: add support for Resource attributes configuration for Prometheus exporter #5122, feat: add metric name translation strategy support for the Prometheus exporter #5118, and feat(exporter/prometheus): add default_aggregation parameter to PrometheusMetricReader #5117 all modify PrometheusMetricReader and _translate_to_prometheus. This is going to conflict with them, we need to coordinate what should be done in order or we'll be bumping into each other with rebases.
4. nit: the nesting depth in _translate_to_prometheus is getting deep — might be worth extracting the per-metric logic into a helper in a follow-up.

Sorry, got a little sloppy with this PR. I originally used _SCOPE_ATTR_CONFLICT_NAMES, but refactored the code so that it isn't needed anymore. The update order shouldn't matter much, I can address the merge conflicts as they come in. Updated the PR description, will clean up the PR.

[herin049]

@MikeGoldsmith I ended up doing a pretty major refactor of the exporter logic based on your suggestion, so we will likely want to merge this PR first.

[MikeGoldsmith]

Looks good, thanks @herin049. Need to update PR title and description.

[ArthurSens]

Hey, just a heads-up from the Prometheus SIG: please hold off on the merge here. There's on going discussion happening on the PR that stabilizes this part of the spec open-telemetry/opentelemetry-specification#5056

[MikeGoldsmith]

Moving to draft until the SIG confirms this is the correct path.