Feature: Executable path expand user and standard env var

[Tilix4]

Changelog Description

Executable path expand user ~ and standard environment variables syntax $ENV_VAR.

Additional info

Fix #1091

Testing notes:

1. In Applications addon, add a ~ or $ENV_VAR (don't forget to set it at some point) to an executable path, like ~/path/to/executable or $HOME/path/to/executable (Unix syntax)