(#38) Add rule for validating ID length

[AdmiringWorm]

Description Of Changes

This implements the note rule CPMR0069, that verifies that the length of
the package identifier is not longer than 20 characters without a dash
between the words.

This implementation is more restrict than what is currently implemented
on Package Validator as it will also consider packages that have certain
extension, just by removing this extension first and it will also verify
that any section between dashes is not longer than 20 characters.

Motivation and Context

To implement rules already present on Package Validator.

Testing

1. Create a nuspec file.
2. Update the identifier to be more than 20 characters.
3. Run choco pack on the created nuspec file.
4. Verify the rule CPMR0069 is flagged.
5. Update the identifier to 19 characters, then add .extension to the identifier (total length should be 29).
6. Run choco pack on the updated nuspec file.
7. Verify tthe rule CPMR0069 is NOT flagged.
8. Update the identifier with an additional character before .extension (total identifier length should be 30).
9. Run choco pack on the updated nuspec file.
10. Verify the rule CPMR0069 is flagged.
11. Update the the identifier to be multiple words split with a dash (-) where all words are less than 20 characters.
12. Run choco pack on the updated nuspec file.
13. Verify the rule CPMR0069 is NOT flagged.
14. Update the identifier again, and make one of the words more than 20 characters.
15. Run choco pack on the updated nuspec file.
16. Verify the rule CPMR0069 is flagged.

Operating Systems Testing

• Windows 10

Change Types Made

• Bug fix (non-breaking change).
• Feature / Enhancement (non-breaking change).
• Breaking change (fix or feature that could cause existing functionality to change).
• Documentation changes.
• PowerShell code changes.

Change Checklist

• Requires a change to the documentation.
• Documentation has been updated.
• Tests to cover my changes, have been added.
• All new and existing tests passed?
• PowerShell code changes: PowerShell v2 compatibility checked?

Related Issue

Fixes #38

[gep13]

LGTM!

[gep13]

@AdmiringWorm Great work! Thanks for getting this added!