Option to install local package from source

[lionel-]

I.e. the equivalent of devtools(build = FALSE). This would be helpful for dev workflows provided by Positron: posit-dev/positron#1733

[gaborcsardi]

To be more precise, I guess what's important for you is not how the package is installed, but that

• the installation is reasonably fast, and
• source references work, both for R and C(++).

Right?

[lionel-]

Yep exactly

[lionel-]

Also optimisations turned off so the C debugger can step-debug in the expected way.