feat: storage node support register and unregsiter for aws aurora cluster

[Xu-Wentao]

Type of change:

• [ ] Bugfix
• [x] New feature provided
• [ ] Improve performance
• [ ] Backport patches

What this PR does / why we need it:

• StorageNode.Spec add Replicas to specify the instance number of cluster.
• StorageNode support register and unregister for aws aurora cluster's primary endpoint automatically. The datasource name of storage unit is combined with ds_ and StorageNode.Name like ds_storage_node_1.

Pre-submission checklist:

• [x] Did you explain what problem does this PR solve? Or what new features have been added?
• [x] Have you added corresponding test cases?
• [ ] Have you modified the corresponding document?

[sonarcloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
1 Code Smell

No Coverage information
0.0% Duplication

[codecov-commenter]

Codecov Report

Merging #398 (8c5509b) into main (e52f093) will decrease coverage by 5.78%. The diff coverage is 12.35%.

@@            Coverage Diff             @@
##             main     #398      +/-   ##
==========================================
- Coverage   47.34%   41.56%   -5.78%     
==========================================
  Files          48       51       +3     
  Lines        5264     6257     +993     
==========================================
+ Hits         2492     2601     +109     
- Misses       2547     3418     +871     
- Partials      225      238      +13     

Impacted Files	Coverage Δ
pitr/agent/internal/handler/backup.go	15.00% <ø> (ø)
pitr/agent/internal/handler/restore.go	0.00% <ø> (ø)
pitr/agent/internal/handler/show.go	0.00% <ø> (ø)
pitr/agent/internal/pkg/opengauss.go	3.93% <ø> (ø)
pitr/agent/internal/pkg/pkg.go	0.00% <ø> (ø)
pitr/agent/pkg/cmds/cmd.go	49.46% <ø> (ø)
pitr/agent/pkg/gsutil/conn.go	29.41% <ø> (ø)
pitr/agent/pkg/strutil/rand_string.go	90.90% <ø> (ø)
pitr/agent/pkg/xerror/error.go	61.53% <ø> (ø)
pitr/cli/internal/cmd/backup.go	73.47% <0.00%> (ø)
... and 26 more

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[wbtlb]

approve

[mlycore]

ref #271