CaiWanting

Results 3 issues of CaiWanting

**What this PR does / why we need it**: Support to add nodes for replica set instance in `huaweicloud_dds_instance`. ## PR Checklist * [x] Tests added/passed. * [x] Documentation updated....

size/S
feature
dependencies

**What this PR does / why we need it**: fix updating public IP ID for rocketmq instance ## PR Checklist * [x] Tests added/passed. * [x] Documentation updated. * [x]...

size/M
bugfix

**What this PR does / why we need it**: support primary standby switch ## PR Checklist * [x] Tests added/passed. ``` make testacc TEST="./huaweicloud/services/acceptance/dds" TESTARGS="-run TestAccDDSPrimaryStandbySwitch_" ==> Checking that code...

size/M
feature