[MRESOLVER-693] Deprecate mvn4 supplier module

**[Tamas Cservenak](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=cstamas)** opened **[MRESOLVER-693](https://issues.apache.org/jira/browse/MRESOLVER-693?redirect=false)** and commented

Once new "standalone Maven API" module materializes and becomes released (lands on Maven Central) the supplier-mvn4 should be deprecated with a message pointing at new "standalone API" artifacts.

Supplier mvn4 anyway used Maven4 in "maven 3 way": via maven-resolver-supplier that IS in Maven 4 compat.

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**Issue Links:**
- [MNG-8637](https://issues.apache.org/jira/browse/MNG-8637) Pull out "Standalone API" from UTs
(_**"requires"**_)

Start by reviewing the linked MNG-8637 issue and confirming when the standalone Maven API artifacts are released to Maven Central. Then locate the supplier-mvn4 module and its use through maven-resolver-supplier. Done means supplier-mvn4 is deprecated with a message pointing to the standalone API artifacts.

Written by the indexing model from the issue text.