Add Windows & macOS Acceptance Tests #3005

Job	Run time
Build (ubuntu-latest, linux)	34s
Build (windows-latest, windows)	9m 3s
Build (macos-latest, macos)	1m 24s
[k3s] demo-helmfile	40s
Docker Lint	19s
Acceptance Tests (ubuntu-latest, linux)	1m 11s
[localstack] demo-localstack	2m 21s
Acceptance Tests (windows-latest, windows)	5m 58s
Acceptance Tests (macos-latest, macos)	1m 38s
[lint] demo-context	10s
[lint] quick-start-advanced	6s
[mock-linux] demo-atlantis	11s
[validate] demo-context	4s
[mock-linux] demo-component-versions	7s
[validate] demo-localstack	4s
[validate] demo-stacks	3s
[mock-linux] demo-context	8s
[validate] demo-helmfile	4s
[mock-linux] demo-vendoring	14s
[validate] quick-start-advanced	4s
[mock-linux] tests	26s
[validate] quick-start-simple	8s
[mock-windows] demo-atlantis	9s
[mock-windows] demo-component-versions	8s
[mock-windows] demo-context	8s
[mock-windows] demo-vendoring	9s
[mock-windows] tests	8s
[mock-macos] demo-atlantis	11s
[mock-macos] demo-component-versions	14s
[mock-macos] demo-context	15s
[mock-macos] demo-vendoring	22s
[mock-macos] tests	31s
release	0s
	27m 12s

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