[image_picker_platform_interface] Add methods for picking both images and videos simultaneously.

[BeMacized]

This PR adds two new functions to the image_picker plugin's platform interface, for picking images and videos from the same native UI.

~~This PR is still in draft mode due to the lack of unit tests. I will be adding tests later.~~

Android and iOS implementations of these new methods can be found here: #4676

Relevant issue:

• flutter/flutter#89159

Pre-launch Checklist

• [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• [x] I read and followed the [relevant style guides] and ran [the auto-formatter]. (Unlike the flutter/flutter repo, the flutter/plugins repo does use dart format.)
• [x] I signed the [CLA].
• [x] The title of the PR starts with the name of the plugin surrounded by square brackets, e.g. [shared_preferences]
• [x] I listed at least one issue that this PR fixes in the description above.
• [x] I updated pubspec.yaml with an appropriate new version according to the [pub versioning philosophy], or this PR is [exempt from version changes].
• [x] I updated CHANGELOG.md to add a description of the change, [following repository CHANGELOG style].
• [x] I updated/added relevant documentation (doc comments with ///).
• [x] I added new tests to check the change I am making, or this PR is [test-exempt].
• [x] All existing and new tests are passing.

[stuartmorgan]

@BeMacized Are you still planning on updating this?

[BeMacized]

Right now, I am not, as I've temporarily been assigned to work on other projects.

[yassinsameh]

@stuartmorgan is it possible to just change your requested renaming of the method, while merging the method with getMultiImage at a later time? It would be great to have this feature live. Great work @BeMacized .

[stuartmorgan]

@yassinsameh It is not possible to land PRs that don't go through a full review cycle, no.

This also wouldn't land without https://github.com/flutter/plugins/pull/4676 being reviewed (per our contribution guide), and if a PR author doesn't currently have time to iterate on a small API PR, then they presumably don't have time to iterate on a PR that's over a thousand lines of diff across 30 files either.

Anyone interested in picking up PRs that the original authors don't currently have time to iterate on is always welcome to do so.

[BeMacized]

Reopening this as I've picked it back up again. Both getImageOrVideo and getMultiImageAndVideo have been replaced by a single getMedia function that takes an options object, which should cover the functionality of any of the other picker functions, as well as allow for mixing videos and images.

[stuartmorgan]

Setting back to draft for now since there are open comments.

[laopaoer-wallet]

is it merged? waiting

[Hixie]

Going to close this one as well for now just to get it off the review queue, but it's still mentioned in the issue in case anyone is ready to pick it up again in due course.