add support for workspace.rc to set custom env

[cgruver]

No description provided.

[etsauer]

so @cgruver you want this setup to be supported in both the developer-base module AND the custom-tooling module?

[cgruver]

so @cgruver you want this setup to be supported in both the developer-base module AND the custom-tooling module?

@etsauer Two different use cases.

1. Developer Base - creates .zshrc and .bashrc in $HOME, if they don't already exist. for example, if the user creates their own persistent $HOME instead of using the container default.
2. Custom Tooling is embedding a default $HOME with .zshrc and .bashrc already created.

[etsauer]

lgtm