More mobile resizing fixes

[ShaneIsrael]

This pull request updates the app version and improves the UI responsiveness and accessibility for both the video and image feeds. The main changes include simplifying the grid layout logic in VideoCards, enhancing the toolbar and selection controls in ImageFeed, and updating the package version.

UI and Responsiveness Improvements:

• Simplified the grid layout in VideoCards.js by removing the single-column logic and ResizeObserver code, and switching to a more responsive gridTemplateColumns definition. This makes the layout easier to maintain and improves responsiveness. [1] [2] [3]
• Improved the toolbar layout in ImageFeed.js for better responsiveness on smaller screens by adjusting the gap property to use responsive values. [1] [2]

Selection Controls and Accessibility:

• Enhanced the select-all button in ImageFeed.js to show icons (DoneAllIcon/RemoveDoneIcon) instead of text on small screens, improving usability on mobile devices. [1] [2]

Version Updates:

• Bumped the app version to 1.7.3 in both package.json and package-lock.json to reflect the new changes. [1] [2]