DMN16 — New Namespace URIs needed

For tools to clearly identify the version of a DMN file or FEEL expression, the XML namespaces of DMN, and FEEL should be updated.

Namespace URIs must be backwards compatible with the scheme applied in previous versions for tools that support multiple versions in parallel. See:

• https://issues.omg.org/browse/DMN12-62?focusedCommentId=18500&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-18500
• DMN13-191
• DMN14-166
• DMN15-160

DMN DI, DI, and DC namespaces can stay the same as DMN 1.6 DI is unchanged since 1.5 and still based on the same DD 1.1 specification and "OMG Policy for Versioning of Specification URIs, File URIs, and XML Namespaces in OMG Specifications", states explicitly:

Note: if a spec has many machine readable files, and only some of them change at a given specification version, then only the changed files should get new URIs. That could mean a mixture of URI date segment values for a given specification version.

Update Namespace URIs for DMN 1.6

Update namespace URIs with the following values:

XSD: https://www.omg.org/spec/DMN/20240513/MODEL/
FEEL: https://www.omg.org/spec/DMN/20240513/FEEL/
XMI: https://www.omg.org/spec/DMN/20240513/DMN16.xmi

These URIs conform to the OMG Policy for Specification URIs and Namespaces (smsc/2018-08-01) and are backwards-compatible with the namespace scheme applied in DMN 1.2, 1.3, 1.4, and 1.5 which is important for vendors supporting multiple versions in parallel.