Clarify primary and secondary actions in DetailedList

[tabibeyal]

The previous documentation described platform behavior in general terms, which was misleading for Android. This update explicitly describes how each platform implements primary and secondary actions: Android uses a long press menu, iOS uses swipe gestures, GTK and macOS use right-click menus, Qt displays standalone buttons, and Windows does not currently support actions.
Fixes: #3727

[johnzhou721]

This looks pretty good already -- a couple of nits, and a direction to extend this in if you're interested.

[tabibeyal]

Below is the latest draft. Are there any additional comments before creating the pull request?

Items in a DetailedList can respond to a primary and secondary action through mechanisms specific to each platform:

* On **Android**, when an item is long-pressed, a menu with the primary and secondary actions is displayed.
* On **iOS**, the primary action is displayed and performed when swiping to the left, and the secondary action is displayed and performed when swiping to the right. 
* On **GTK**, a right click on the selected row, displays the buttons for primary and secondary action.
* On **macOS**, a right click on the selected row, displays a context menu with the primary and secondary actions.
* On **Qt**, primary and secondary actions are displayed as buttons shown in the rows of the DetailedList.
* On **Windows**, the implementation does not currently support primary or secondary actions.

The primary and secondary actions will only be enabled in the DetailedList UI if a handler has been provided.

[mhsmith]

If you do want to update the "refresh" documentation, then you might as well do it in this PR. There's no point in creating a separate one.

Some CI checks failed: you can see them at the bottom of the PR page, and you should also have received an email. Follow the links for instructions on how to resolve them.

[mhsmith]

Also, please don't click the "resolve conversation" button; let the person who started the conversation do that. Automatic resolution when accepting a suggestion is OK.

[tabibeyal]

Also, please don't click the "resolve conversation" button; let the person who started the conversation do that. Automatic resolution when accepting a suggestion is OK.

Sure, no problem, I'm still learning the platform, thanks for letting me know.

[tabibeyal]

If you do want to update the "refresh" documentation, then you might as well do it in this PR. There's no point in creating a separate one.

Some CI checks failed: you can see them at the bottom of the PR page, and you should also have received an email. Follow the links for instructions on how to resolve them.

I resolved the CI errors and started working on "refresh" documentation,

[mhsmith]

Items don't respond to a refresh action, hence the phrase "as a whole" further down.

[mhsmith]

Minor updates to the documentation should go in the misc category so they don't clutter the release notes.

[mhsmith]

These are both "pull-down" interactions, there's no need to make a distinction based on the hardware.

[mhsmith]

I've fixed the remaining issues. Thanks for the contribution!

[tabibeyal]

It was a great experience, thanks for being patient with me.