[exporterhelper, exporterqueue] Deprecate unused public symbols

[jade-guiton-dd]

Description

To help stabilize the exporter module faster, this PR deprecates some public symbols from exporterhelper and the entirety of exporterqueue, which don't seem to be used by anyone on Github, so that they might be fully internalized in a future release.

(Another option would be removing them entirely, if some aren't used internally. Yet another would be moving them to a new module as suggested by #11143, if it turns out some are currently in use in the ecosystem.)

All the symbols involved were introduced by #8122; of the symbols introduced by that PR, only WithBatcher is used in the ecosystem, and thus isn't deprecated by this PR. It has a variable argument of type BatcherOption, which is deprecated as it isn't used. A future release should remove this variable argument.

To avoid the linter complaining about internal use of deprecated symbols, exporterqueue functionality was split into an internal package with most of the functionality, and deprecated aliases in the old exporterqueue package. The new internal package is exporter/internal/exporterqueue instead of exporter/exporterqueue/internal, to allow its internal use by exporter/exporterhelper.

An issue arose with the aliasing process: exporterqueue exports multiple generic types, but generic aliases are only supported starting from Go 1.23. So, unless we wish to update the Go version soon, the only option was to declare a different defined type, and convert at runtime between the two in the alias function shims. There is some surprising behavior in exactly which equivalent types Go allows to convert between, which leads to some strange code in said shims.

Link to tracking issue

Updates #11142

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 15 lines in your changes missing coverage. Please review.

Project coverage is 91.86%. Comparing base (5ac1607) to head (f8d9243).
Report is 87 commits behind head on main.

Files with missing lines	Patch %	Lines
exporter/exporterqueue/queue.go	0.00%	11 Missing ⚠️
exporter/exporterhelper/common.go	0.00%	3 Missing ⚠️
exporter/exporterqueue/config.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11285      +/-   ##
==========================================
- Coverage   91.91%   91.86%   -0.06%     
==========================================
  Files         432      434       +2     
  Lines       20350    20371      +21     
==========================================
+ Hits        18705    18713       +8     
- Misses       1271     1285      +14     
+ Partials      374      373       -1     

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[mx-psi]

Looks good, just one comment about deprecating the whole of exporterqueue

[bogdandrutu]

I don't think we should "delete" everything that is not used. Please at least consider to wait until @dmitryax reviews and approves this.

[jade-guiton-dd]

@dmitryax do you have an opinion on how we should proceed regarding the batching API?

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.