feat(*): Support string length validation

[ragi-dayananda]

Closes accordproject/concerto#643

Changes

• Add concepts for string length validator for string property and string scalar property
• Update test points for the changes.

Author Checklist

• Ensure you provide a DCO sign-off for your commits using the --signoff option of git commit.
• Vital features and changes captured in unit and/or integration tests
• Commits messages follow AP format
• Extend the documentation, if necessary
• Merging to main from fork:branchname

[coveralls]

Pull Request Test Coverage Report for Build 4988808314

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 94.03%

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Totals
Change from base Build 4935291883:	0.0%
Covered Lines:	83
Relevant Lines:	84

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💛 - Coveralls

[dselman]

Note that because this is still version 1.0.0 of the metamodel any existing code or clients that has been coded against the 1.0.0 version of the metamodel (or validates it...) must ignore these new optional properties.

I think this is ok - but it is somewhat risky, depending on how we roll out these changes across the stack.