add loop target fields and localization for loop functionality

[hugou74130]

This pull request enhances the semantic workflow loop input controls by improving user feedback, localization, and internal state tracking. The main focus is to provide better UI cues and ensure changes to loop settings are accurately detected and handled. Additionally, it introduces new localized strings for loop targets and cleans up some debug output.

Loop input control improvements:

• The controls_for_loop function now returns a boolean indicating if any changes were made, ensuring that updates to the loop state (such as toggling, count changes, or target selection) are tracked and trigger appropriate UI updates. [1] [2] [3] [4]
• Added a tooltip for the loop target selection button to improve user guidance.

Localization:

• Added new localized strings for "Loop Target" and its tooltip in both English (en_US.lua) and French (fr_FR.lua). [1] [2] [3]

UI and icon updates:

• Registered a new loop icon for use in the UI.

Code cleanup:

• Removed unnecessary debug print statements from input selection and loop evaluation logic. [1] [2]

@FramePerfection

[FramePerfection]

It would be nice to see which inputs invoke loops in the input list at a glance, and when a looping input is selected, it'd be nice to mark its loop target in the input list as well somehow (e.g. with a blue frame or something).

I can try my hand at that myself if you can't get around to it though.

[FramePerfection]

It appears that this icon is the cycle from google's Material Symbols library.
https://fonts.google.com/icons?selected=Material+Symbols+Outlined:cycle:FILL@0;wght@400;GRAD@0;opsz@24&icon.query=arrow&icon.set=Material+Symbols&icon.size=24&icon.color=%23e3e3e3

As this is licensed under Apache 2.0, the license needs to be added to the repository and distributions for this file specifically.