Add omni schema plugin's validation code for transform_declarations

[jf-tech]

No description provided.

[codecov]

Codecov Report

Merging #20 into master will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##            master       #20    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           15        16     +1     
  Lines          332       505   +173     
==========================================
+ Hits           332       505   +173     

Impacted Files	Coverage Δ
omniparser/schemaplugin/omni/v2/plugin.go	100.00% <ø> (ø)
omniparser/schemaplugin/omni/v2/transform/decl.go	100.00% <ø> (ø)
...iparser/schemaplugin/omni/v2/transform/validate.go	100.00% <100.00%> (ø)
strs/strs.go	100.00% <100.00%> (ø)

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