Run a component's release command before the deploy switches current (S-005-1..7, 10, 11) #119

Builds part of spec S-005, docs/specs/005-release-command.md (feature issue #88): the acceptance criteria below. Each needs a test that names its id (test_s005_<k>_..., or a proves: S-005-1 comment line).

This is the schema, the validation, and the release command in the deploy role.

• S-005-1: A component with release.command that creates a table deploys with cloudfall deploy --yes, the table exists afterwards, and the release receipt has releaseCommand with the command, exitCode: 0 and an outputTail
• S-005-2: The command runs after the Materialize locked dependencies for the release task and before the Install the managed service unit and Switch the current release symlink tasks, as the application's linuxUser, with the new release directory (or its workingDirectory) as its working directory
• S-005-3: A release command that prints every variable sees each key of the installed <installRoot>/shared/env/<component>.env, values with the same quoting rules the unit applies
• S-005-4: A release command that exits 1 makes deploy --yes exit ENGINE_STEP_FAILED with an error.message naming the release command and exit code 1; current still points at the previous release on every server, the unit file is unchanged, the service was not restarted, and no release receipt was written
• S-005-5: A release command still running after timeoutSeconds is stopped and fails the deploy the same way, with an error.message naming the timeout
• S-005-6: With deployment.servers: [b, a], the command runs once, on b, before either server's current moves, and every release receipt from that deploy names b in releaseCommand.server
• S-005-7: releaseCommand.outputTail holds at most the last 2000 characters of a command that prints more
• S-005-10: A component without release deploys with the same Ansible tasks as before and a receipt with no releaseCommand
• S-005-11: config validate exits CONFIG_INVALID for a release.workingDirectory that is absolute or contains .., an empty release.command, or a timeoutSeconds outside 1 to 1800