[2.0] add semantictests: all `bom-ref` must be of type `refType`

[jkowalleck]

goals:

• add a test, that checks that ALL properties bom-ref properties are of type cyclonedx-common-2.0.schema.json#$defs/refType
• add a test, that checks that ONLY properties bom-ref properties are of type cyclonedx-common-2.0.schema.json#$defs/refType

automation:

• tests must run on every PR
• tests must be executable locally

out of scope:

• altering schemas or tests - done in different issue/PR

[jkowalleck]

done per #1000 & #1001