Feat: add support for LPG

[kral2]

Fix #38

• each vcn can have one or many lpg
• peer_id argument is supported and optional
• route_table_id is supported and optional

new example using this feature to build hub-and-spoke.

[hyder]

In a previous release, you also added a drg attachment : https://github.com/oracle-terraform-modules/terraform-oci-vcn/blob/main/vcn_gateways.tf#L207. See also issue #44

The problem is the following:

1. A VCN can have only 1 DRG at a time but a DRG can have multiple attachment.
2. The DRG attachment that is currently created in the VCN attaches the VCN to this DRG. However, we may need to specify additional parameters such as network details: See here: https://registry.terraform.io/providers/hashicorp/oci/latest/docs/resources/core_drg_attachment
3. This is particularly relevant if have a firewall in the hub and we therefore need to specify a private IP address in a custom route table and attach this route table to the drg_attachment.

The drg_attachment should therefore be able to accept custom route table ids. Currently, it does not.

[kral2]

In a previous release, you also added a drg attachment : https://github.com/oracle-terraform-modules/terraform-oci-vcn/blob/main/vcn_gateways.tf#L207. See also issue #44

The problem is the following:

1. A VCN can have only 1 DRG at a time but a DRG can have multiple attachment.

2. The DRG attachment that is currently created in the VCN attaches the VCN to this DRG. However, we may need to specify additional parameters such as network details: See here: https://registry.terraform.io/providers/hashicorp/oci/latest/docs/resources/core_drg_attachment

3. This is particularly relevant if have a firewall in the hub and we therefore need to specify a private IP address in a custom route table and attach this route table to the drg_attachment.

The drg_attachment should therefore be able to accept custom route table ids. Currently, it does not.

This PR is related to issue #38 only: creating and controlling LPGs. The DRG attachment problem is related to the new capabilities of the DRG and should be handled in a different issue. #46 opened for this subject and should probably be addressed together with #44 in the same PR.

[hyder]

In the root terraform.tfvars.example, you need to provide a commented example of how these 2 variables will look like:

• local_peering_gateways
• internet_gateway_route_rules
• nat_gateway_route_rules

In terraformoptions doc, you also need to add for:

• local_peering_gateways

[hyder]

approved. some minor grammatical mistakes in the docs but we can fix that later