Vendorize dandi-cli per config in server info

[candleindark]

This PR brings new features to allow the DANDI client to vendorize itself according to a DANDI sever instance it interacts with. It closes #1660.

TODOs:

• Fetch server instance config JSON from a given DANDI server instance
• Reconstruct server instance config object from the server with validation
• [x] Set the instance config in the CLI initialization process
• [ ] Implement way to save the DANDI server instance choice across different executions of commands
• [ ] Implement a command to allow user to set server instance choice
• Ensure dandishcema.models is not loaded at the start of each command that can take an instance option
  • This involves delaying import of dandishcema.models in numerous modules
• Make sure the dandischema dependency is not longer pointing to Vendor-Configurable Metadata Models dandi-schema#294

Release Notes

1. DUMMY_DANDI_ETAG and DUMMY_DANDI_ZARR_CHECKSUM in dandi/misctypes.py are replaced with get_dummy_dandi_etag() and get_dummy_dandi_zarr_checksum in order to delay the import of dandischema.models.

[codecov]

Codecov Report

Attention: Patch coverage is 74.02597% with 20 lines in your changes missing coverage. Please review.

Project coverage is 66.75%. Comparing base (03b7c07) to head (066e16e).

Files with missing lines	Patch %	Lines
dandi/cli/base.py	50.00%	8 Missing ⚠️
dandi/files/bases.py	64.28%	5 Missing ⚠️
dandi/cli/cmd_ls.py	0.00%	1 Missing ⚠️
dandi/dandiset.py	0.00%	1 Missing ⚠️
dandi/files/bids.py	66.66%	1 Missing ⚠️
dandi/files/zarr.py	85.71%	1 Missing ⚠️
dandi/metadata/nwb.py	50.00%	1 Missing ⚠️
dandi/misctypes.py	91.66%	1 Missing ⚠️
dandi/tests/test_metadata.py	50.00%	1 Missing ⚠️

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HEAD has 552 uploads less than BASE

Flag	BASE (03b7c07)	HEAD (066e16e)
unittests	553	1

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #1661       +/-   ##
===========================================
- Coverage   88.84%   66.75%   -22.10%     
===========================================
  Files          83       83               
  Lines       11515    11537       +22     
===========================================
- Hits        10230     7701     -2529     
- Misses       1285     3836     +2551     

Flag	Coverage Δ
unittests	66.75% <74.02%> (-22.10%)	⬇️

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[candleindark]

@yarikoptic I have successfully delayed the import of dandischema.models in dandi-cli such that each command starts with dandischema.models not yet imported. Now I can insert code at the start of each command to set the instance config defined in dandischema.conf before a possible import of dandischema.models in the execution of the command. As you can see, the code relies on the ID of a known DANDI instance.

The commands in the following files have the instance_option, so what instance to use to set the instance config is clear, with the exception of cmd_download.py which involves some indirect logic.

1. dandi/cli/cmd_delete.py
2. dandi/cli/cmd_download.py
3. dandi/cli/cmd_move.py
4. dandi/cli/cmd_service_scripts.py
5. dandi/cli/cmd_upload.py

On the other hand, the commands in the following files lack the instance_option, and what instance to use to set the instance config is unclear, or undetermined.

1. dandi/cli/cmd_digest.py
2. dandi/cli/cmd_instances.py
3. dandi/cli/cmd_ls.py
4. dandi/cli/cmd_organize.py
5. dandi/cli/cmd_shell_completion.py
6. dandi/cli/cmd_validate.py

Not all commands in these files need to import dandischema.models, but dandi/cli/cmd_ls.py, dandi/cli/cmd_organize.py, and dandi/cli/cmd_validate.py most likely do. We need to decide which DANDI instance to use to set the instance config in those that do.

In coming up with that decision, we may want to consider changing the interface and/or design of this client. We may want to have a centralized command that configures the client to be associated with a DANDI instance, and use the instance to set the instance config in subsequent command executions.