feat: partial support of build field in compose for kube quadlets

[axel7083]

Description

Given a compose file

name: flask-compose
services:
  backend:
    build:
      context: flask

the podlet compose --kube would give the following

# flask-compose.kube
[Kube]
PodmanArgs=--build=true
Yaml=flask-compose-kube.yaml

[Service]
WorkingDirectory=/home/axel7083/github/fosdem2025/demo-quadlet

---

# flask-compose-kube.yaml
apiVersion: v1
kind: Pod
metadata:
 name: flask-compose
spec:
 containers:
 - image: flask
   name: backend

How ?

1. Detect if Compose spec has services with the build option.
2. Add the WorkingDirectory to the [Service] section of the systemd unit (take the parent of the compose file).
3. Adding the --build true to the podman args