add XML schema definition for the DebugBundle
feature #12336 [DebugBundle] add XML schema definition for the DebugBundle (xabbuh)

This PR was merged into the 2.6-dev branch.

Discussion
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[DebugBundle] add XML schema definition for the DebugBundle

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Commits
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d9c239d add XML schema definition for the DebugBundle