feat: per workspace timeout

[publicqi]

This PR introduces a per-workspace timeout configuration

[pr2502]

hi, i don't mind the idea of making it possible to override certain options on a per-workspace basis, but i don't like this approach. at the very least i think the option name should be more generic than per_workspace_timeout, we probably want to allow to override other options like pass_environment, not just instance_timeout. but generally i think having to specify every workspace configuration in one central configuration file is rather unergonomic and for example reading a config file from the project directory would be a better UX