FINERACT-2875: Take the template id from the path on update - #6539

Description

JIRA: https://issues.apache.org/jira/browse/FINERACT-2875

PUT /v1/templates/{templateId} updates the template whose id is in the request body, not the one in the URL, and it rejects a request without a body id with an untranslated validation message:

• PUT /v1/templates/1 with {"id": 2, ...} returns {"resourceId": 2} and updates template 2; template 1 is unchanged.
• PUT /v1/templates/1 without id returns 400 with the raw key {org.apache.fineract.infrastructure.template.id.not-null} as the error message.

TemplatesApiResource.saveTemplate receives the templateId path parameter but never copies it onto the TemplateUpdateRequest before dispatching TemplateUpdateCommand, and TemplateDomainServiceImpl.updateTemplate loads the template by request.getId(). TemplateUpdateRequest.id is @NotNull, so the body id is mandatory, and that constraint's message key is not defined in ValidationMessages.properties.

This PR:

• sets the payload id from the path in saveTemplate, as deleteTemplate already does;
• removes the @NotNull on TemplateUpdateRequest.id (bean validation runs before the method body, so it would otherwise keep the body id mandatory);
• adds the missing org.apache.fineract.infrastructure.template.id.not-null message, which TemplateDeleteRequest still uses.

A client that already sends the matching id in the body is unaffected.

Testing

• New test in TemplatesApiResourceTest: saveTemplate(34L, request) with body id 99 dispatches a payload with id 34. On develop it fails (expected: 34L but was: 99L); with this PR all 5 tests in the class pass.
• Live on a local PostgreSQL instance booted with bootRun, with two freshly created templates:
  • develop (213f517b88): PUT /v1/templates/1 with body id: 2 returns 200 {"resourceId": 2} and renames template 2; the same request without id returns 400 with the raw message key above.
  • With this PR (templates 3 and 4): PUT /v1/templates/3 with body id: 4 and without id both return 200 {"resourceId": 3} and update template 3; template 4 is unchanged.
• spotlessJavaCheck passes.

Checklist

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• Add required Swagger annotation and update API documentation at fineract-provider/src/main/resources/static/legacy-docs/apiLive.htm with details of any API changes (not applicable: no endpoint or schema change; the body id is no longer required and is ignored)
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