Added a Resetview Option Feature

[vinayakjeet]

#1666

Overview

This pull request introduces a "Reset View" option to Avogadro, enabling users to easily revert the view to its default state. This includes resetting the camera angles, the origin of the coordinate system, and the zoom level.

Changes

• GLWidget: Added resetViewSettings() to reset camera and view-related settings.
• MultiViewWidget: Implemented resetAllViews() to propagate the reset across all embedded view widgets.

Purpose

The addition of this feature enhances usability by providing a straightforward way to reset views, especially useful when switching between molecules or configurations. This mirrors the behavior seen when switching between molecules in the Molecules pane, where the view resets to a default state.

closes #1666

[vinayakjeet]

@ghutchis @matterhorn103 Please note, that this PR includes changes from PR #1659. Please review and merge PR #1659 first to simplify the process.