CLI: Setup autoenabled OpenNeuro special remote during upload if one doesn't exist

[nellh]

For the Deno CLI, this adds the missing steps required to configure a special remote.

The remote is always named "OpenNeuro" and git-annex get is all that's required for annexed objects if you have configured the OpenNeuro special remote already. This also includes annex branch handling for starting from a dataset not created server side by OpenNeuro (meaning you can upload without cloning first theoretically but we always clone to check if one exists).

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 202 lines in your changes are missing coverage. Please review.

Project coverage is 42.21%. Comparing base (9afe434) to head (786ebee).
Report is 2 commits behind head on master.

Files	Patch %	Lines
cli/src/worker/git.ts	0.00%	163 Missing ⚠️
cli/src/worker/types/git-context.ts	0.00%	22 Missing ⚠️
cli/src/worker/annex.ts	0.00%	17 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3063      +/-   ##
==========================================
- Coverage   42.42%   42.21%   -0.21%     
==========================================
  Files         601      601              
  Lines       37939    38126     +187     
  Branches     1113     1113              
==========================================
  Hits        16095    16095              
- Misses      21628    21815     +187     
  Partials      216      216              

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