Add RegionTargetHttp(s)Proxy, RegionSslCertificate to compute

[modular-magician]

Original Author: @tysen

`google_compute_region_ssl_certificate`
release-note:new-resource
`google_compute_region_target_http_proxy`
release-note:new-resource
`google_compute_region_target_https_proxy`
release-note:enhancement
compute: added `foo_bar` field to `google_compute_foo` resource
release-note:bug
container: fixed perma-diff in `google_container_cluster`
release-note:breaking-change
project: made `iam_policy` authoritative
release-note:deprecation
container: deprecated `region` and `zone` on `google_container_unicorn`. Use `location` instead.
release-note:new-resource
`google_compute_new_resource`
release-note:new-datasource
`google_compute_new_datasource`
release-note:new-resource
`google_compute_region_ssl_certificate`
release-note:new-resource
`google_compute_region_target_http_proxy`
release-note:new-resource
`google_compute_region_target_https_proxy`

`google_compute_region_ssl_certificate`

`google_compute_region_target_http_proxy`

`google_compute_region_target_https_proxy`