Substitute parameters before validation

[eliaskoromilas]

Description

docker app build/validate does not involve parameter substitution -> false negatives

Steps to reproduce the issue:

1. docker-compose.yml

version: '3.2'
services:
  hello-world:
    image: hello-world
    volumes:
    - ${test}:/path/to/bar

2. parameters.yml

test: /path/to/foo

3. docker app build . / docker app validate

Describe the results you received:

Compose file validation failed:
* can't use relative path as volume source ("${test}:/path/to/bar") in service "hello-world"

Describe the results you expected:

Validated "hello-world.dockerapp"

Output of docker version:

Docker version 20.10.5, build 55c4c88

Output of docker app version:

Version:               v0.9.1-beta3
Git commit:            9d2c67f8
OS/Arch:               linux/amd64