mod_rest: Fix nested message stanzas in XEP-0297 containers It's all a bit awkward because it doesn't normally use the whole schema directly, but rather checks which stanza type is used and picks out that property as a schema. Which also prevents references from working.

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summary: Allow server administrators to probe any user
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This module lets server administrators send `<presence type="probe"/>`
to any local user and receive their presence in response, bypassing
roster checks.