cloud: New output v2

[codebien]

It adds the foundation for a new cloud output versioned as v2.

It depends on the following PRs as a prerequisite:

• cloud/v1: Aggregation in a dedicated pkg #3063
• output/cloud: Versioning #3041 Support multiple versions of the output

[codecov-commenter]

Codecov Report

Merging #3072 (7cf7dab) into master (06e1628) will increase coverage by 0.01%.
The diff coverage is 78.57%.

❗ Current head 7cf7dab differs from pull request most recent head 545dbe4. Consider uploading reports for the commit 545dbe4 to get more accurate results

@@            Coverage Diff             @@
##           master    #3072      +/-   ##
==========================================
+ Coverage   75.29%   75.31%   +0.01%     
==========================================
  Files         232      233       +1     
  Lines       17593    17607      +14     
==========================================
+ Hits        13247    13260      +13     
- Misses       3494     3495       +1     
  Partials      852      852              

Flag	Coverage Δ
ubuntu	75.31% <78.57%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
output/cloud/expv2/output.go	75.00% <75.00%> (ø)
output/cloud/output.go	76.87% <100.00%> (+0.31%)	⬆️

... and 1 file with indirect coverage changes

[na--]

I know this doesn't have any of the logic, but just wanted to 👍 the general versioning approach

[imiric]

@codebien Is this PR ready for review? I've been ignoring it since it's marked as draft.

[codebien]

@imiric not really, the attempt here is to collect all the other PRs and then do a single merge to master. Of course, without really reviewing it because we reviewed the smaller PRs.

[mstoykov]

If we are going to get this merged before all the other get merged, maybe drop the closes #number issue parts of the PR description?

[codebien]

Description updated