feat(swr): add datasource SWR shared accounts

[luoping-12345]

What this PR does / why we need it: add datasource SWR shared accounts

Which issue this PR fixes: (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged) fixes #xxx

Special notes for your reviewer:

Release note:

add datasource SWR shared accounts

PR Checklist

• [x] Tests added/passed.
• [x] Documentation updated.
• [x] Schema updated.

Acceptance Steps Performed

make testacc TEST="./huaweicloud/services/acceptance/swr" TESTARGS="-run TestAccDataSourceSharedAccounts_basic"
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./huaweicloud/services/acceptance/swr -v -run TestAccDataSourceSharedAccounts_basic -timeout 360m -parallel 4
=== RUN   TestAccDataSourceSharedAccounts_basic
=== PAUSE TestAccDataSourceSharedAccounts_basic
=== CONT  TestAccDataSourceSharedAccounts_basic
--- PASS: TestAccDataSourceSharedAccounts_basic (53.87s)
PASS
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/swr       53.939s