ci: add test workflow

[goncalo-frade-iohk]

Fixes ATL-1642

[github-actions]

MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ ACTION	actionlint	1		0	0.06s
✅ REPOSITORY	checkov	yes		no	4.81s
✅ REPOSITORY	devskim	yes		no	0.66s
✅ REPOSITORY	dustilock	yes		no	0.01s
✅ REPOSITORY	gitleaks	yes		no	0.13s
✅ REPOSITORY	git_diff	yes		no	0.0s
✅ REPOSITORY	secretlint	yes		no	0.97s
✅ REPOSITORY	syft	yes		no	0.4s
✅ REPOSITORY	trivy	yes		no	2.58s
✅ YAML	prettier	1		0	0.62s
✅ YAML	v8r	1		0	1.8s
✅ YAML	yamllint	1		0	0.1s

See errors details in artifact MegaLinter reports on CI Job page
Set VALIDATE_ALL_CODEBASE: true in mega-linter.yml to validate all sources, not only the diff