add ability to bring your own EM project id or name the created project

[displague]

Adds the ability to bring your own Equinix Metal Project ID.

• Organization ID is now required, If creating a project. The project name can now be specified or use the existing randomly generated name.

• Project ID can now be specified. When specified, set metal_create_project to false.

• Fixes the integration test by defining the needed GitHub secrets

• Makes the test ephemeral. Hashicorp's external state is no longer used, a project creation and sweeping action is used.

Fixes #54 (not sure how, but the tests should help confirm) Fixes #50

[displague]

The automation now gets significantly further:

Error: Could not find matching reserved block, all IPs were []

  on ProviderNetwork.tf line 6, in data "metal_precreated_ip_block" "private_ipv4":
   6: data "metal_precreated_ip_block" "private_ipv4" {

Error: Could not find matching reserved block, all IPs were []

  on ProviderNetwork.tf line 24, in data "metal_precreated_ip_block" "public_ipv6":
  24: data "metal_precreated_ip_block" "public_ipv6" {

I'll open a new issue for this. Merging this PR.