feat(cae/app): add new resource to manage applications

[Lance52259]

What this PR does / why we need it:
Add new resource to manage applications.

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:

1. add new resource support to manage applications.
2. add related document and acceptance test.

PR Checklist

• Tests added/passed.

./scripts/coverage.sh -o cae -f TestAccApplication_basic
Prepare to calculate the coverage the following command:
TF_ACC=1 go test "./huaweicloud/services/acceptance/cae" -v -coverprofile="./huaweicloud/services/acceptance/cae/cae_coverage.cov" -coverpkg="./huaweicloud/services/cae" -run TestAccApplication_basic -timeout 360m -parallel 10
=== RUN   TestAccApplication_basic
--- PASS: TestAccApplication_basic (467.67s)
PASS
coverage: 25.3% of statements in ./huaweicloud/services/cae
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/cae       467.742s        coverage: 25.3% of statements in ./huaweicloud/services/cae

• Documentation updated.

• Schema updated.

• CheckDeleted.

  • a. During query operation (Read Context)
    aa. Resource not found
    

    ab. Related resources (parent resources) not found
    

  • b. During delete/disassociate/unbind operation (Delete Context)
    ba. Resource not found
    

    bb. Related resources (parent resources) not found
    

[github-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This PR has been approved by: @Lance52259

[deer-hang]

/lgtm