feat: apply rule @typescript-eslint/explicit-member-accessibility

[legendecas]

Which problem is this PR solving?

• Identifying pitfalls like fix(instrumentation-openai)!: add missing access modifiers to private methods #3242 earlier.

Short description of the changes

Given that applying the private access modifier could be a potential breaking change, this does not apply the rule to every package to reduce the burden of reviewers.

• Apply rule @typescript-eslint/explicit-member-accessibility to (non-instrumentation) packages (less changes).

[github-actions]

This package does not have an assigned component owner and is considered unmaintained. As such this package is in feature-freeze and this PR will be closed with 14 days unless a new owner or a sponsor (a member of @open-telemetry/javascript-approvers) for the feature is found. It is the responsibility of the author to find a sponsor for this feature.
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[JamieDanielson]

Nice cleanup, looks like those constants aren't used here and are already being exported in utils.

[JamieDanielson]

Should this be marked as breaking since there are some private modifiers being added in where they weren't previously?

[pichlermarc]

Looks good overall, but I think we may have to undo the changes from public to private in packages/resource-detector-aws, as the package is already stable.