Clean up lightly.api docs

[michal-lightly]

What has changed and why?

Removed deprecated and internal api functions from the generated docs.

Closes #1375.

How has it been tested?

• Locally built the docs. Checked that entries are missing.
• Checksum: There are 24 entries to remove and 24x added a line with :meta private:

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (afced0a) 85.41% compared to head (9f1e788) 85.41%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1385   +/-   ##
=======================================
  Coverage   85.41%   85.41%           
=======================================
  Files         130      130           
  Lines        5465     5465           
=======================================
  Hits         4668     4668           
  Misses        797      797           

Files Changed	Coverage Δ
lightly/api/api_workflow_client.py	98.97% <ø> (ø)
lightly/api/api_workflow_compute_worker.py	96.25% <ø> (ø)
lightly/api/api_workflow_datasources.py	93.54% <ø> (ø)
lightly/api/api_workflow_predictions.py	100.00% <ø> (ø)
lightly/api/api_workflow_selection.py	83.63% <ø> (ø)
lightly/api/api_workflow_tags.py	96.29% <ø> (ø)
lightly/api/api_workflow_upload_embeddings.py	88.42% <ø> (ø)
lightly/api/api_workflow_upload_metadata.py	90.56% <ø> (ø)
lightly/utils/io.py	91.22% <ø> (ø)

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