refactor: deploy subnets for every az in aws (#330)

subnets are regional in azure and gcp, so we're mimicking that behavior in aws
this means:
- subnets in aws generate 1 subnet for each availability zone
- for regional and highly available resources (kubernetes node pool and databases for now) we use all generated AWS subnets
- for zonal resources (vms, network interfaces), a zone is selected and the appropriate subnet with it
- for resources that are associated with single subnets (route table associations) we create 1 for each subnet

Author: goncalo-rodrigues

api/proto/resourcespb/database.pb.go

@@ -44,6 +44,7 @@ message DatabaseArgs {
   string password = 8;
   repeated string subnet_ids = 9;
   int32 port = 10;
+  string subnet_id = 11;
 }
 
 message DatabaseResource {
@@ -57,6 +58,7 @@ message DatabaseResource {
   string password = 8;
   repeated string subnet_ids = 9;
   int32 port = 12;
+  string subnet_id = 13;
 
   //outputs
   string host = 10;

api/proto/resourcespb/database.proto

@@ -31,11 +31,13 @@ message NetworkInterfaceArgs {
   string name = 2;
   string subnet_id = 3;
   string public_ip_id = 4;
+  int32 availability_zone = 5;
 }
 
 message NetworkInterfaceResource {
   common.CommonResourceParameters common_parameters = 1;
   string name = 2;
   string subnet_id = 3;
   string public_ip_id = 4;
+  int32 availability_zone = 5;
 }