GEOS-11850 Pretty-print text/mapml responses based on global verbose XML setting

[prushforth]

This PR gives the user the ability to pretty-print text/mapml responses that have not yet been cached. This helps the developer what is going on in MapML documents in general, one of the main goals of integrating support for text/mapml into GeoServer. It leverages the Global menu setting for 'verbose' (readable) XML responses as a flag for pretty-printing.

Checklist

• I have read the contribution guidelines.
• I have sent a Contribution Licence Agreement (not required for small changes, e.g., fixing typos in documentation).
• First PR targets the main branch (backports managed later; ignore for branch specific issues).

For core and extension modules:

• New unit tests have been added covering the changes.
• Documentation has been updated (if change is visible to end users).
• The REST API docs have been updated (when changing configuration objects or the REST controllers).
• There is an issue in the GeoServer Jira (except for changes that do not affect administrators or end users in any way).
• Commit message(s) must be in the form [GEOS-XYZWV] Title of the Jira ticket.
• Bug fixes and small new features are presented as a single commit.
• Each commit has a single objective (if there are multiple commits, each has a separate JIRA ticket describing its goal).

The PR will be merged when all the build checks are green (see automated QA checks), there is a code committer review, and the checklist has been fulfilled.