Create kie-platform-bom

We currently use the following Maven pom hierarchy:

kie-parent-metadata
kie-parent-with-dependencies extends kie-parent-metadata
    -> imports ip-bom
    -> imports kie-bom
    -> imports drools-bom
    -> imports optaplanner-bom
    -> overwrites batik
    -> additional artifact versions in depMgmt
drools extends kie-parent-with-dependencies
drools-core extends drools

Effectively our platform BOM is kie-parent-with-dependencies. The name is unfortunately a bit misleading. After a discussion with gdesmet@redhat.com we agreed that it would be great to create a kie-platform-bom that would basically contain the same contents as currently kie-parent-with-dependencies. Users can then use this BOM (with a disclaimer that is it a platform BOM) if they want to have all our versions available (also the 3rd party ones that are not in our current BOMs). This BOM will be imported in kie-parent-with-dependencies. All others projects should still use the

for now as we want to decrease the overall impact of the change. In future (probably 7.0) we would like to remove the kie-parent-with-dependencies completely and have only kie-parent (the metadata parent) and kie-platform-bom which contains all the different versions of our and also 3rd party deps.

This is the expected result (for the near future):

kie-parent-metadata
kie-platform-bom // Add comment "there can only be 1 platform bom in your dep tree"
    -> imports ip-bom
    -> imports kie-bom
    -> imports drools-bom
    -> imports optaplanner-bom
    -> overwrites batik
    -> additional artifact versions in depMgmt
kie-parent-with-dependencies extends kie-parent-metadata
    -> imports kie-platform-bom
drools extends kie-parent-with-dependencies
drools-core extends drools
optaplanner extends kie-parent-with-dependencies
optaplanner-core extends optaplanner