chore(blobs): Validate Index field in BlobSidecar during processing

[shotes]

This PR adds validation of Index field in BlobSidecars.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.

Project coverage is 30.85%. Comparing base (7e5f02d) to head (705a204).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
da/blob/verifier.go	0.00%	5 Missing ⚠️
da/types/sidecar.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2289      +/-   ##
==========================================
- Coverage   30.87%   30.85%   -0.02%     
==========================================
  Files         333      333              
  Lines       15230    15237       +7     
  Branches       20       20              
==========================================
  Hits         4702     4702              
- Misses      10203    10210       +7     
  Partials      325      325              

Files with missing lines	Coverage Δ
da/types/sidecar.go	78.18% <0.00%> (-2.96%)	⬇️
da/blob/verifier.go	0.00% <0.00%> (ø)