reinstate `make install-deps` or similar for developer convenience

[rocodes]

Description

Developer quality of life:
Sometimes it's helpful to be able to test out client code in sd-app by allowing network access, cloning the client repo, and running a branch of the client against a provisioned system. This will be sped up if we have a make target that installs everything that's needed (git, make, rust toolchain, libssl-dev, pkg-config, python3-dev, python3-poetry, off the top of my head but there may be more) so that devs can get going quickly.

How will this impact SecureDrop users?

developer facing

How would this affect the SecureDrop Workstation threat model?

n/a

User Stories

As a developer I want to be able to quickly boostrap a temporary environment (sd-app)

[cfm]

I have most of this in https://github.com/cfm/dotfiles/blob/af3750fb5c262602de340a50532d1a5639dd6266/Makefile#L114-L134 and would be happy to slim it down to just the required set.

[eloquence]

Keeping open: probably not something we need for the legacy client at this point, but we may want it in some form for the new app. See also freedomofpress/securedrop-dev-docs#245 for associated docs.