Show PostFeaturedImage in editor

[ntsekouras]

Description

Fixes: #25410

Currently when you insert a PostFeaturedImage block is displayed only a placeholder.
This PR displays the image properly.

There are going to be follow up PRs to enhance this block's functionality, like the selecting size, add link etc..

How has this been tested?

Locally.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR.

[github-actions]

Size Change: -30.2 kB (2%)

Total Size: 1.17 MB

Filename	Size	Change
build/a11y/index.js	1.14 kB	+1 B
build/annotations/index.js	3.52 kB	-1 B
build/api-fetch/index.js	3.35 kB	+17 B (0%)
build/block-directory/index.js	8.61 kB	+206 B (2%)
build/block-editor/index.js	129 kB	+746 B (0%)
build/block-editor/style-rtl.css	11.1 kB	-2 B (0%)
build/block-editor/style.css	11.1 kB	-1 B
build/block-library/editor-rtl.css	8.6 kB	+10 B (0%)
build/block-library/editor.css	8.6 kB	+9 B (0%)
build/block-library/index.js	135 kB	-81 B (0%)
build/block-library/style-rtl.css	7.61 kB	+9 B (0%)
build/block-library/style.css	7.6 kB	+12 B (0%)
build/block-serialization-default-parser/index.js	1.78 kB	+2 B (0%)
build/blocks/index.js	47.5 kB	-55 B (0%)
build/components/index.js	168 kB	-33.7 kB (20%)	🎉
build/components/style-rtl.css	15.4 kB	-72 B (0%)
build/components/style.css	15.4 kB	-72 B (0%)
build/compose/index.js	9.42 kB	-1 B
build/core-data/index.js	12 kB	+25 B (0%)
build/data-controls/index.js	1.27 kB	+1 B
build/data/index.js	8.42 kB	-7 B (0%)
build/date/index.js	31.9 kB	-2 B (0%)
build/dom/index.js	4.42 kB	-20 B (0%)
build/edit-navigation/index.js	10.7 kB	+253 B (2%)
build/edit-post/index.js	306 kB	+19 B (0%)
build/edit-post/style-rtl.css	6.25 kB	+15 B (0%)
build/edit-post/style.css	6.24 kB	+15 B (0%)
build/edit-site/index.js	20.5 kB	+920 B (4%)
build/edit-site/style-rtl.css	3.54 kB	+244 B (6%)	🔍
build/edit-site/style.css	3.54 kB	+242 B (6%)	🔍
build/edit-widgets/index.js	18.1 kB	+1.13 kB (6%)	🔍
build/edit-widgets/style-rtl.css	2.81 kB	+21 B (0%)
build/edit-widgets/style.css	2.81 kB	+20 B (0%)
build/editor/index.js	45.4 kB	+108 B (0%)
build/editor/style-rtl.css	3.83 kB	+28 B (0%)
build/editor/style.css	3.82 kB	+26 B (0%)
build/element/index.js	4.44 kB	-8 B (0%)
build/format-library/index.js	7.49 kB	+3 B (0%)
build/html-entities/index.js	621 B	-1 B
build/i18n/index.js	3.55 kB	+1 B
build/is-shallow-equal/index.js	709 B	-2 B (0%)
build/list-reusable-blocks/index.js	3.02 kB	+1 B
build/notices/index.js	1.69 kB	-1 B
build/plugins/index.js	2.44 kB	+2 B (0%)
build/rich-text/index.js	13.5 kB	-227 B (1%)
build/server-side-render/index.js	2.6 kB	-1 B
build/url/index.js	4.06 kB	-1 B
build/viewport/index.js	1.74 kB	-1 B
build/warning/index.js	1.13 kB	+1 B

ℹ️ View Unchanged

Filename	Size	Change
build/autop/index.js	2.72 kB	0 B
build/blob/index.js	620 B	0 B
build/block-directory/style-rtl.css	943 B	0 B
build/block-directory/style.css	942 B	0 B
build/block-library/theme-rtl.css	741 B	0 B
build/block-library/theme.css	741 B	0 B
build/block-serialization-spec-parser/index.js	3.1 kB	0 B
build/deprecated/index.js	772 B	0 B
build/dom-ready/index.js	568 B	0 B
build/edit-navigation/style-rtl.css	868 B	0 B
build/edit-navigation/style.css	871 B	0 B
build/editor/editor-styles-rtl.css	492 B	0 B
build/editor/editor-styles.css	493 B	0 B
build/escape-html/index.js	733 B	0 B
build/format-library/style-rtl.css	547 B	0 B
build/format-library/style.css	548 B	0 B
build/hooks/index.js	1.74 kB	0 B
build/keyboard-shortcuts/index.js	2.39 kB	0 B
build/keycodes/index.js	1.85 kB	0 B
build/list-reusable-blocks/style-rtl.css	476 B	0 B
build/list-reusable-blocks/style.css	476 B	0 B
build/media-utils/index.js	5.12 kB	0 B
build/nux/index.js	3.27 kB	0 B
build/nux/style-rtl.css	671 B	0 B
build/nux/style.css	668 B	0 B
build/primitives/index.js	1.34 kB	0 B
build/priority-queue/index.js	789 B	0 B
build/redux-routine/index.js	2.85 kB	0 B
build/shortcode/index.js	1.7 kB	0 B
build/token-list/index.js	1.24 kB	0 B
build/wordcount/index.js	1.17 kB	0 B

_{compressed-size-action}

[mcsf]

I'll leave it up to you to manage how much of the design improvements you want to get in this PR vs. subsequent PRs. I hereby unblock you. :D

[ntsekouras]

Thanks @mcsf 👍 ! I'll wait for some feedback from @jasmussen 's ping here: #25412 (comment) and we'll see how it goes from there.