Add CLI and checks for time-point selection

[daniel-thom]

This extends code from @KwamiS. It is draft because some things don't work correctly.

Adds:

• CLI utility
• Checks for circuit element values before & after changing load shape values, which fails.
• Checks for final load shape values, which fail because PV load shapes aren't being modified.
• Creates a partial metadata file. The existing code does not identify the condition represented by each time point.
• tests

@KwamiS Also, your branch is very outdated. I had to merge main into this. You should do the same to yours.

[daniel-thom]

Closing because GitHub is now confused on the branch history.