Add custom escript runner configuration option

[Mikaka27]

Hi,

This is basically a copy and finish of #136.
Motivation for this change is to better support remote development in vscode.

Reasoning:

1. In erlang/otp repository there is .devcontainer configuration. However it is not usable in it's current form.
   It is based on ubuntu image which installs otp 22 from ubuntu repositories, then it downloads 3 last versions of erlang from kerl.
   However you cannot choose which one of those to use, since vscode cannot execute an additional command when entering the dev container. You can of course modify the container configuration, but each time you want to do that, you would need to rebuild the container.

2. Internally in other projects some of the people use remote ssh to develop erlang code. However the environment is not configured to work with remote ssh development. Upon opening the repository, we must run initialization script that adds correct erlang to path.
   However vscode cannot do that, it must have this erlang set somehow. Workaround is to set this erlang path in .bashrc file, but this has the problem that it is a global change, but we would like to have this settable per workspace.
   This pull request would achieve it.

[plux]

Thanks for your contribution @Mikaka27