exec-host does not resolve env variables in commands

[jonaseberle]

Is your feature request related to a problem? Please describe.
I was trying to add the current user's .gitconfig to .ddev/homeadditions in a pre-start hook.

I expected something like this to work

- exec-host: |
  [ -e ~/.gitconfig ] && cp -L ~/.gitconfig .ddev/homeadditions/

(problems with [ paranthesis)

- exec-host: |
  [[ -e ~/.gitconfig ]] && cp -L ~/.gitconfig .ddev/homeadditions/

bashism anyways, but does not resolve ~ to home user directory

- exec-host: echo ~
- exec-host: echo $HOME

(outputs "~" "$HOME")

Tried running it though bash

- exec-host: bash -c "echo $HOME"

(outputs $HOME": -c: Zeile 0: End of file encountered while looking fo »"«
$HOME": -c: Zeile 1: Syntax error: Unexpected EOF.)

Describe the solution you'd like
It would be nice if the command string in there was just eval'ed without further escaping and the like.

Describe alternatives you've considered
Just run a bash file which does the job. In there you are not restricted.

Additional context
It might be difficult to make that cross-platform - if yes, I suggest adding a line to the documentation with the suggestion to use an external file before building complex commands in there ;)