The `cli-test-env.sh` script has a `==` comparison operator, which is a
non-POSIX extension.
This commit replaces it with the `=` POSIX operator, enabling it to be sourced
from a wider variety of shells (namely zsh for this commit's author).
* Tools shim maker and env path handling
Includes component:
* Given executable, create shim (all three OSs)
* Add executable path to Env PATH during first run
* including manual instruction when there is no access
