Support line-through and underlining, textDecorationLine on <Text> components

[jmcginty]

The following textDecoration works on ios, but not on Windows.

<Text style={{ textDecorationLine: 'line-through' }} >
          This text should be struck out
</Text>
<Text style={{ textDecorationLine: 'underline' }} >
          This text should be underlined
</Text>

<Text style={{ textDecorationLine: 'underline line-through' }} >
          This text should be underlined and struck out
</Text>

In the react-native doco, textDecorationLine can be one of ..
['none' /default/, 'underline', 'line-through', 'underline line-through'] )

[rozele]

Thanks @jmcginty. UWP has an "Underline" span type, but does not have a Strikethrough span type. We haven't yet added the underline feature.

[rozele]

Most of this can be supported as of RS3 with APIs demonstrated in #1723. We just need to update the target and ensure that we do ApiInformation checks to make sure the target is RS3 or later.

[ghost]

We are not investing in new features or lower priority bug fixes on vCurrent. The bulk of investment is now in vNext as we prepare to make that the default choice. If this issue is still relevant on the vNext implementation please open a vNext issue. If this issue is of significant severity for a vCurrent app and vNext is not an option, re-open with justification.