feat(fgs): supplement attributes for function resources

[wangyuancheng01]

What this PR does / why we need it:
feat(fgs): supplement attributes for function resources.

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:

PR Checklist

• Tests added/passed.
• Documentation updated.
• Schema updated.

Acceptance Steps Performed

make testacc TEST="./huaweicloud/services/acceptance/fgs" TESTARGS="-run TestAccFgsV2Function_funcVpcAndNetworkController"
...
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./huaweicloud/services/acceptance/fgs -v -run TestAccFgsV2Function_funcVpcAndNetworkController -timeout 360m -parallel 4
=== RUN   TestAccFgsV2Function_funcVpcAndNetworkController
=== PAUSE TestAccFgsV2Function_funcVpcAndNetworkController
=== CONT  TestAccFgsV2Function_funcVpcAndNetworkController
--- PASS: TestAccFgsV2Function_funcVpcAndNetworkController (92.69s)
PASS
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/fgs       92.753s