Set `codegen-tools` to be a dependency of `deep-copy`

[t-eckert]

Description

I just ran into this when running deep-copy for the first time. While it didn't take me too long to figure out, I did spend a minute figuring out what what wrong when the error I got was originally a bit esoteric (raised from the ./agent/structs/deep-copy.sh script).

I thought I would save future devs the moments of confusion with a helpful error.

Testing & Reproduction steps

Have deep-copy not installed (rm $(which deep-copy) works) then run make deep-copy. You will get the error deep-copy not found. Please run 'make codegen-tools' to install it.

PR Checklist

• ~[ ] updated test coverage~
• ~[ ] external facing docs updated~
• ~[ ] not a security concern~

[t-eckert]

This seems fine but alternatively this could just depend on the tools make target which should install the tool.

That is a much better idea!