Allow setting custom IntGrid values

[billylegota]

This pull request introduces the ability for users to edit IntGridValueDef values through an input field, while ensuring proper validation and rule updates.

Closes #1083.

Overview:

• Changed value indicator to an input field in editLayerDefs.html
• Added IntInput to the value input field with the following:
  • Validation rule: LayerDef.isIntGridValueValid ensures that 0 < value <= 999 and no other IntGridValueDef on this layer uses the same value.
  • On invalid: Created new notification invalidValue.
  • Setter: calls new method, updateIntGridValue, on the current layer instance with the old and new value.
• Added updateIntGridValue method to LayerInstance which does the following:
  • Updates the IntGridValueDef to change the value.
  • Updates all stored values by calling setIntGrid.
  • Updates the current layer's definition's auto rules (as the patterns need to be updated with the new value).
  • Updates the auto rules for all levels whose auto source is this layer (not combined with the previous step as the current layer does not have a reference to itself in autoSourceLayerDefUid).

Notes:

• Changing the value indicator to an input field altered the text formatting slightly, but I am unsure how to restore the original formatting. I can look into it further if needed.
• The range validation is currently handled in LayerDef.isIntGridValueValid to centralize the logic across the layer. If preferred, I can refactor this to use IntInput.setBounds for inline validation.
• The invalidValue notification uses similar messaging to invalidIdentifier. However, I can modify it to explicitly state the value restrictions (e.g., "Value must be a positive integer less than 1000 and unique within the layer.") if you'd prefer a more detailed message.
• I tried to keep the code style as close as I could to the existing code. Let me know if you have any recommendations.

Example Usage:

Below is an example of updating the IntGridValueDef, including verification that changes are properly reflected in the map, auto rules, and when reloading the file.

Initial IntGrid settings:

Selecting the value for the IntGridValueDef we want to update:

Changing the value to 2:

Verifying that the map has updated:

Verifying that the rules have updated:

Verifying that the contents are preserved when loading the file again:

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By submitting this pull request, I hereby assign all copyright and related rights in the changes contained in this pull request to the maintainer(s) of this project, to the extent permitted by law.