👌 Improve schema severity handling

[ubmarco]

Various schema reporting improvements:

• Remove setting needs_schema_severity
• Output all violations to console unless suppressed by suppress_warnings
• Introduce severity based log type, so they can specifically be suppressed
  • info: sn_schema_info
  • warning: sn_schema_warning
  • violation: sn_schema_violation
• Severity info and warning is logged as logger.warning()
• Severity violation is logged as logger.error() for a different color
• Changes to schema_violations.json
  • Write all violations, irrespective of the severity and suppress_warnings
  • The log_lvl information reflect what Sphinx does.
    Possible values are warning or error.
  • Do not output log_lvl and type for children.
    This information is only required on the root, the nested fields are duplicates.
  • Do not print need IDs that have no warnings
• Do not print Field: in schema console reports if not set
• Update docs and tests accordingly

Fixes: #1553

[codecov]

Codecov Report

❌ Patch coverage is 91.13924% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.96%. Comparing base (4e10030) to head (22a8d8c).
⚠️ Report is 187 commits behind head on master.

Files with missing lines	Patch %	Lines
sphinx_needs/schema/reporting.py	90.62%	6 Missing ⚠️
sphinx_needs/logging.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1561      +/-   ##
==========================================
+ Coverage   86.87%   87.96%   +1.08%     
==========================================
  Files          56       70      +14     
  Lines        6532     9638    +3106     
==========================================
+ Hits         5675     8478    +2803     
- Misses        857     1160     +303     

Flag	Coverage Δ
pytests	87.96% <91.13%> (+1.08%)	⬆️

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[chrisjsewell]

From the description, that all looks fine, but unfortunately I don't have time to go through the code in detail

[MrChocolateMoose]

Approved, but there is some minor typos and a clarification I had that would be helpful to handle prior to merging.