Add textInfos unit mappings for UIA document, page and format field, make FORMATFIELD and CONTROLFIELD units global

[LeonarddeR]

Link to issue number:

None

Summary of the issue:

The _UIAHandler.NVDAUnitsToUIAUnits mapping is incomplete, not containing document and page.

Description of how this pull request fixes the issue:

I added these units. I also discovered that we have TextUNitFormat, which is equivalent to NVDA format fields. Therefore, I moved the UNIT_CONTROLFIELD and UNIT_FORMATFIELD units from VirtualBufferTextINfo to the textInfos package. This should make the code more consistent and also fixes a theoretical bug where BrowseModeDocumentTreeInterceptor.event_caretMovementFailed tried to use UNIT_CONTROLFIELD on a TextInfo that didn't have this constant.

Testing performed:

Tested that in Word with UIA enabled, I can expand to page, story and format field.

Known issues with pull request:

None

Change log entry:

• Changes for developers
  • The UNIT_CONTROLFIELD and UNIT_FORMATFIELD constants have been moved from virtualBuffers.VirtualBufferTextInfo to the textInfos package.
  • UIA TextInfo objects can now be moved/expanded by the page, story and formatField text units.

[LeonarddeR]

Added this to the 2019.3 milestone because the pr is pretty small and includes a backwards incompatible change.