Add Groovy markup templating support to the MVC config [SPR-11998]

[spring-projects-issues]

Rossen Stoyanchev opened SPR-11998 and commented

Since we now have support for view resolution in the MVC config, we should add support for Groovy Markup templates alongside the other built-in templating technologies.

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Affects: 4.0.6

This issue is a sub-task of #16411

Referenced from: commits 80f4ea1