resource okta_app_bookmark authentication_policy argument

[monde]

Related to Bookmark Application Sign-On Policy #1352
This PR is a continuation of @jakezarobsky-8451's PR #1366 that included:

• Added authentication_policy argument to resource okta_app_bookmark
• Updated documentation for resource okta_app_bookmark
• Start of ITs

Specific to this PR:

• Clean up original PR
• Add a specific PR test
• Add an example config

for t in `grep "func Test" okta/resource_okta_app_bookmark_test.go | awk '{ print $2}'| sed -e 's/(.*//g'`; do
TF_ACC=1 go test -tags unit -mod=readonly -test.v -run ^${t}$ ./okta
done
=== RUN   TestAccAppBookmarkApplication_crud
--- PASS: TestAccAppBookmarkApplication_crud (11.26s)
PASS
ok      github.com/okta/terraform-provider-okta/okta    12.154s
=== RUN   TestAccAppBookmarkApplication_timeouts
--- PASS: TestAccAppBookmarkApplication_timeouts (4.71s)
PASS
ok      github.com/okta/terraform-provider-okta/okta    5.256s
=== RUN   TestAccAppBookmarkApplication_PR1366_authentication_policy
--- PASS: TestAccAppBookmarkApplication_PR1366_authentication_policy (6.76s)
PASS
ok      github.com/okta/terraform-provider-okta/okta    7.195s