[BugFix] - dev_install.py updates

[montezdesousa]

1. Why?

   • dev_install.py uses toml which needs to be manually installed in each environment, it's not in the dependency tree

2. What?

   • Replace it with tomlkit which is used by poetry, thus it's already in the dependency tree
   • Added a Loading... print statement to cli main since the application cold start takes a while and looks hanged

3. Impact

   • No need to pip install toml anymore, pip install poetry and it will work

4. Testing Done:

   • python dev_install.py
   • python dev_install.py -e

[hjoaquim]

Behaves as intended!