Stabilize configopaque

[atoulme]

Before stabilizing a module, an approver or maintainer must make sure that the following criteria have been met for at least two successive minor version releases:

Edited by @mx-psi on 2023-01-12 to add three two more issues

• No open issues or PRs in the module that would require breaking changes\
  • Should configopaque.String implement encoding.BinaryMarshaler? #9272
  • Document configopaque security expectations #9274
• No TODOs in the module code that would require breaking changes
• No deprecated symbols in the module
• No symbols marked as experimental in the module
• The module follows the Coding guidelines

Please also make sure to publicly announce our intent to stabilize the module on:

• The #otel-collector CNCF Slack Channel
• The #opentelemetry CNCF Slack channel
• A Collector SIG meeting (if unable to attend, just add to the agenda)

To help other people verify the above criteria, please link to the announcement and other links used to complete the above in a comment on this issue.

Once all criteria are met, close this issue by moving this module to the stable module set.

[atoulme]

Added to agenda of SIG meeting on Jan 3, 2024: https://docs.google.com/document/d/1r2JC5MB7GupCE7N32EwGEXs9V_YIsPgoFiLP4VWVMkE/edit

[atoulme]

#otel-collector announcement https://cloud-native.slack.com/archives/C01N6P7KR6W/p1704235222655319
#opentelemetry announcement https://cloud-native.slack.com/archives/CJFCJHG4Q/p1704235248182969

[mx-psi]

We should think about redacting also on String method based on the discussion on open-telemetry/opentelemetry-collector-contrib#29446 (comment). I have not looked into this but I think it's a good idea.

cc @codeboten @martin-majlis-s1

[atoulme]

I have opened #9213 to follow up.

[atoulme]

I am not aware of any other work needing to take place on this package ; please speak up if you see anything else worth addressing.
In particular, I have reviewed the code and have found that it matches coding best practices, but a more experienced reviewer should do another pass.
If everything is squared away, then this package can be considered stable in 2 minor releases, after 0.94.0 is out.

[mx-psi]

I did another pass and filed #9271 so that we also redact the output when using %#v and have a bit more thorough tests.

Two remaining issues IMO:

• Should configopaque.String implement encoding.BinaryMarshaler? #9272
• Document configopaque security expectations #9274