Add a separate parameter for `tools` under `packages`

[rakshitgondwal]

About

We currently have packages.runtime to include our runtime dependencies and packages.dev to include our dev dependencies.
A new packages.tools parameter should be created which will include all the dependencies/tools a user would require for CI actions or the ones that should not be included in the OCI image by default.
These packages should be included in the devShell as well.

We should also allow users to include these tools packages in the base image as well. By default, we shouldn't template packages.tools in the oci.layers field but if a user wants he/she should be able to add that.

Dod

• A new tools param in the packages block is created. Users can add a package to tools via bsf search.
• Modify the devShells template to loop over the tools packages as well.
• packages.tools can be defined inoci.layers.
• Update unit tests.