[orca-list] Orca now optionally announces when entering and leaving blockquotes, lists, and tables

[Joanmarie Diggs <jdiggs igalia com>]

Hey all.

I've just committed a change to master to optionally announce when
entering and leaving blockquotes, lists, and tables. Details:

* Announcement is enabled by default, for both navigation and Say All
* Announcement of each object type is independent (e.g. you can enable
  blockquotes, but disable tables and lists)
* Announcement during navigation is independent of announcement during
  Say All (e.g. you can have blockquotes announced during navigation but
  not when using Say All, and tables announced during Say All but not
  during navigation)
* At this time, announcement during Structural Navigation is not
  impacted by these changes. Thus disabling list announcement during
  navigation will not stop Orca from announcing list details when L is
  used to move to the next list. This is intentional.
* In order for this functionality to work, the application or toolkit
  needs to expose the objects to us correctly. For example, LibreOffice
  Writer exposes list items using ROLE_PARAGRAPH; not ROLE_LIST_ITEM. It
  also fails to expose any parent container with ROLE_LIST. This makes
  it difficult to reliably identify the start and end of lists, doubly
  so due to other LibreOffice accessibility bugs. The situation is
  similar for blockquotes. We aren't attempting sad, fragile hacks to
  work around these LibreOffice issues.

I'm sure there are bugs. Please test. Thanks!
--joanie