Unit tests for JSON Schema of CSDL JSON

[ralfhandl]

Schema changes:

• added schemas for SimpleIdentifier and QualifiedName and used them where appropriate
• used "simple identifier" pattern for schema children, structured type properties, enum members, and container children
• used "qualified name" pattern for schema names
• made $Version required on document root
• fixed a spelling error

Cleanup

• run test workflow only with Node 16.x
• recommend code spell checker extension
• add some words to the cspell dictionary
• depend on AJV directly, no longer on AJV CLI and thus indirectly on AJV
• removed use of AJV CLI
• added unit tests for csdl.schema.json using AJV

[HeikoTheissen]

Perhaps add test cases for valid/invalid identifiers?

[ralfhandl]

Perhaps add test cases for valid/invalid identifiers?

Already there:

• invalid schema name
• invalid schema child name
• invalid property name (entity type)
• invalid property type name

Added:

• invalid property name (complex type)
• invalid enumeration member name
• invalid action parameter name
• invalid function parameter name

[HeikoTheissen]

Found an error in Org.OData.Capabilities.V1.permissions-sample.xml.

[ralfhandl]

Found an error in Org.OData.Capabilities.V1.permissions-sample.xml.

We fixed that with oasis-tcs/odata-vocabularies#170