Add Create Rule API Logic

[ruai0511]

Description

This PR introduces the create Rule API Logic.

An exampe API request is:

curl -XPUT "localhost:9200/_wlm/rule" -H 'Content-Type: application/json' -d '    
{
     "index_pattern": ["log*", "event*"],
     "query_group": "dev_query_group_id_2"
}'

And the return would be

{
    "_id":"zLKS95QBqTh9lO4Pl_FO",
    "index_pattern":["log*","event*"],
    "query_group":"dev_query_group_id_2",
    "updated_at":"2025-02-12T00:32:46.586Z"
}

Rule Schema PR:
#17238
RFC:
#16797

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

[github-actions]

❌ Gradle check result for bab1e6e: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

❌ Gradle check result for 3c4c098: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?