Set Default state to media library for library button in image block

[akasunil]

In Gutenberg Image Block, on click of 'Media Library' button it should open Media Library tab in Media Popup. Instead, it open last opened tab. It confusing for user when they specifically click Media Library button and end up on upload tab in media Popup.

What?

Fixes #41473

Testing Instructions

Please follow step by step instructions to test this PR.

1. Create new post.
2. Add Image block.
3. Click Media Library button.
4. Click on Upload Tab
5. Close Popup and click Media Library button.
6. Make sure it open Media Library tab in Dialog.

Screenshots or screencast

[glendaviesnz]

This tested well for me. Should we document the mode prop here.

[glendaviesnz]

Tested on Image, Gallery and Cover block and worked correctly on all. Thanks for this fix 🎉

[akasunil]

Thank you. glendaviesnz.

[akasunil]

@Mamaduka Can you please review the PR. Thank you.

[Mamaduka]

@sunil25393, it looks like this was already reviewed by @glendaviesnz. So I'm going to merge the PR.

[mburridge]

Added the Needs Dev Note label in case this needs a dev note (either individual or as part of a "misc" dev note) for WP 6.1 release.