[api_gateway] Unable to specify multi-level routes

[szilveszter]

The current implementation of the api_gateway module won't allow using /s in the routes:

routes = {
  "/multi-level/path" = {
    lambda_key = "rest_api_handler"
  }
}

This results in the following error during terraform apply:

│ Error: creating API Gateway Resource: BadRequestException: Resource's path part only allow a-zA-Z0-9._-: or a valid greedy path variable and curly braces at the beginning and the end.
│ 
│   with module.main.module.rest_api_gateway.aws_api_gateway_resource.rest_api_route_resource["multi-level/path"],
│   on .terraform/modules/main.rest_api_gateway/modules/api_gateway/main.tf line 146, in resource "aws_api_gateway_resource" "rest_api_route_resource":
│  146: resource "aws_api_gateway_resource" "rest_api_route_resource" {

[explorigin]

Solved up to 5 levels via #29