NIFI-14343 Replaced IdentifyMimeType property descriptors Config File and Config Body with one property descriptor using identifiesExternalResource.

[dan-s1]

Summary

NIFI-14343
This PR removes the two property descriptors Config File and Config Body and replaces it with a single property descriptor which uses identifiesExternalResource which thereby allows a single property descriptor to support a configuration body, configuration file path or a configuration specified by a URL. In addition validation was added to ensure if a custom configuration is replacing the defaults or being merged with the defaults that it is indeed a valid configuration. This PR no longer supports expression language for this new property descriptor since if if a file path is specified in an attribute, it will be treated as a configuration body and not a file path.

Tracking

Please complete the following tracking steps prior to pull request creation.

Issue Tracking

• Apache NiFi Jira issue created

Pull Request Tracking

• Pull Request title starts with Apache NiFi Jira issue number, such as NIFI-00000
• Pull Request commit message starts with Apache NiFi Jira issue number, as such NIFI-00000

Pull Request Formatting

• Pull Request based on current revision of the main branch
• Pull Request refers to a feature branch with one commit containing changes

Verification

Please indicate the verification steps performed prior to pull request creation.

Build

• Build completed using mvn clean install -P contrib-check
  • JDK 21

Licensing

• New dependencies are compatible with the Apache License 2.0 according to the License Policy
• New dependencies are documented in applicable LICENSE and NOTICE files

Documentation

• Documentation formatting appears as expected in rendered files