fix: prevent widgets from losing configuration after changing grid size (issue #197)

[svenburkard]

Type of change(s)

• Bug fix
• Feature / enhancement
• Infrastructure / tooling (CI, build, deps, tests)
• Documentation

What changed and why

• Looking at older commits, it looks to me like deleting widget IDs on grid resize was added to prevent previous resize-related widget crashes.
• Later, widget IDs were saved in the database so they can be reused.
• With that newer behavior, deleting IDs during grid resize now causes problems and widgets lose their configuration after changing rows or columns.
• This PR keeps widget IDs on grid resize, so widgets do not lose their configuration on a grid resize.

Tests performed

• Adding some widgets on a fresh upstream Launcher version.
• I used "Simple Crypto Widget" from F-Droid and because of multiple users reporting issues in a different widget related bug report (Disappearing Widgets #146) I also used a widget from "Breezy Weather" from F-Droid.
• Increase row count from 6 to 7.
• Both widgets losing their configurations.
• Resizing the widgets still work for me.
• Repeating the same tests with the changes of this PR and seeing that widgets do not lose their configuration anymore and widget resizing still does work.

Before & after preview

• Before:
  https://github.com/user-attachments/assets/4ceedef2-883b-408b-b7a1-59117cf352ad

• After:
  https://github.com/user-attachments/assets/72170f7f-55d0-4fda-8955-fb15252270fd

Closes the following issue(s)

• Closes Widgets not resizeable after increasing rows #197

Checklist

• I read the contribution guidelines.
• I manually tested my changes on device/emulator (if applicable).
• I updated the "Unreleased" section in CHANGELOG.md (if applicable).
• I have self-reviewed my pull request (no typos, formatting errors, etc.).
• I understand every change in this pull request.