feat: add resource/datasource cloudavenue_edgegateway_security_group

[azrod]

Description of your changes

Add new resource and datasource cloudavenue_edgegateway_security_group

If you submit change in the provider code, please make sure to:

• Write or modify examples in examples/ directory
• Write or modify acceptance tests
• Run make generate to ensure the doc was updated properly

How has this code been tested

Resource

 TF_ACC=1 go test -v -count=1 -timeout 720m  -run TestAccSecurityGroupResource  ./internal/tests/edgegw
=== RUN   TestAccSecurityGroupResource
--- PASS: TestAccSecurityGroupResource (168.52s)
PASS
ok      github.com/orange-cloudavenue/terraform-provider-cloudavenue/internal/tests/edgegw      169.029s

Datasource

TF_ACC=1 go test -v -count=1 -timeout 720m  -run TestAccSecurityGroupDataSource  ./internal/tests/edgegw
=== RUN   TestAccSecurityGroupDataSource
--- PASS: TestAccSecurityGroupDataSource (91.60s)
PASS
ok      github.com/orange-cloudavenue/terraform-provider-cloudavenue/internal/tests/edgegw      92.167s

[crown-app]

Thank you for your contribution, but this PR exceeds the recommended size of 1000 lines. Please make sure you are NOT addressing multiple issues with one PR.
Note this PR might be rejected due to its size.