Add endpoint to trigger MoSAPI metrics export

[njshah301]

This commit introduces a new backend endpoint at /_dr/task/triggerMosApiServiceState that initiates the process of fetching the latest service states for all TLDs from the MoSAPI endpoint and exporting them as metrics to Cloud Monitoring.

The key changes include:
- A new TriggerServiceStateAction class that handles the GET request to the new endpoint.
- Logic within MosApiStateService to concurrently fetch states for all configured TLDs.
- A new MosApiMetrics class (currently a placeholder) responsible for sending the collected states to the monitoring service.
- Unit tests for the new action and the updated service logic.

This endpoint will be called periodically to ensure that the MosApi service health metrics are kept up-to-date.

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This change is 

[CydeWeys]

@CydeWeys made 1 comment.
Reviewable status: 0 of 7 files reviewed, 1 unresolved discussion (waiting on @gbrodman, @njshah301, and @ptkach).

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core/src/main/java/google/registry/mosapi/TriggerServiceStateAction.java line 51 at r2 (raw file):

    response.setContentType(MediaType.PLAIN_TEXT_UTF_8);
    try {
      stateService.triggerMetricsForAllServiceStateSummaries();

It's often helpful to have a single INFO logging line in advance of doing all the work. Something like "Beginning fetch of MoSAPI metrics for all TLDs."

[CydeWeys]

@CydeWeys reviewed 7 files and all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @gbrodman, @njshah301, and @ptkach).