fix(rls api): Add missing init file

[jfrag1]

SUMMARY

We're seeing problems deploying as a result of this

File ".../superset/initialization/__init__.py", line 153, in init_views
    from superset.row_level_security.api import RLSRestApi
ModuleNotFoundError: No module named 'superset.row_level_security'

Several linting errors were undetected as a result of this too, the PR resolves these

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #23817 (d34f151) into master (60c2e70) will decrease coverage by 2.28%.
The diff coverage is 75.00%.

❗ Current head d34f151 differs from pull request most recent head 77ff67a. Consider uploading reports for the commit 77ff67a to get more accurate results

@@            Coverage Diff             @@
##           master   #23817      +/-   ##
==========================================
- Coverage   67.91%   65.63%   -2.28%     
==========================================
  Files        1936     1936              
  Lines       74929    74929              
  Branches     8141     8141              
==========================================
- Hits        50886    49183    -1703     
- Misses      21955    23658    +1703     
  Partials     2088     2088              

Flag	Coverage Δ
hive	53.00% <50.00%> (?)
mysql	?
postgres	?
presto	52.92% <50.00%> (ø)
python	77.74% <75.00%> (-4.70%)	⬇️
sqlite	77.39% <75.00%> (?)
unit	?

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

Impacted Files	Coverage Δ
superset/row_level_security/schemas.py	100.00% <ø> (ø)
superset/row_level_security/commands/update.py	91.66% <50.00%> (ø)
superset/row_level_security/commands/create.py	100.00% <100.00%> (ø)

... and 123 files with indirect coverage changes

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[Antonio-RiveroMartnez]

LGTM