Add start to SSM json schemas

[kddejong]

Issue #, if available:
#2728

Description of changes:

• Add rule E3051 to validate SSM document structure

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[codecov]

Codecov Report

Attention: Patch coverage is 96.55172% with 1 line in your changes missing coverage. Please review.

Project coverage is 93.40%. Comparing base (ee6271f) to head (f0e592e).

Files	Patch %	Lines
src/cfnlint/rules/resources/ssm/Document.py	96.55%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3471      +/-   ##
==========================================
- Coverage   93.40%   93.40%   -0.01%     
==========================================
  Files         325      326       +1     
  Lines       11087    11116      +29     
  Branches     2327     2331       +4     
==========================================
+ Hits        10356    10383      +27     
  Misses        410      410              
- Partials      321      323       +2     

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