Add support for x-strong attribute in USFM

[PhotoNomad0]

@elsylambert - latest build translationCore 3.4.1 (17ff357) has this update:

Test by enabling pre-release and then selecting for download:

and then for en:

Then open a Titus project (such as https://git.door43.org/unfoldingWord/en_ult/raw/branch/master/57-TIT.usfm) and for WA GL then en unfoldingWord

Launch WA and for 1:15 click on all the words in the alignment area and make sure non of the strongs numbers are empty:

[elsylambert]

Looks good and works as expected(as per the test instructions above^^) in translationCore 3.4.1 (https://github.com/unfoldingWord/translationCore/commit/5ed21f7da0dccdf7118bcf66129942ff68e92762) . All Original words have strong numbers.