[Enhancement](Backup) support show create repository

[GoGoWen]

Proposed changes

Issue Number: close #xxx

Problem summary

Describe your changes.

support show create repository stmt.

SQL example: show create repository for repo_name Result: MySQL [(none)]> show create repository for doris_backup_backup_cluster_bt1; +---------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | RepoName | CreateStmt | +---------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | doris_backup_backup_cluster_bt1 | create read only repository doris_backup_backup_cluster_bt1 with broker broker_name on location "hdfs://ns1017/user/jd_ad/ads_report/narwal_backup/backup_cluster" properties ("password" = "XXXX","dfs.client.failover.proxy.provider" = "org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider","dfs.ha.namenodes.ns1017" = "nn1,nn2","dfs.namenode.rpc-address.ns1017.nn2" = "XXXXXX:8020","dfs.nameservices" = "ns1017","dfs.namenode.rpc-address.ns1017.nn1" = "XXXXX:8020","username" = "XXXX") | +---------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

Checklist(Required)

• [N ] Does it affect the original behavior
• [ N] Has unit tests been added
• [N ] Has document been added or modified
• [N ] Does it need to update dependencies
• [Y] Is this PR support rollback (If NO, please explain WHY)

Further comments

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