Upgrade to LibLouis 3.0.0 #6109

Hi,

LibLouis 3.0.0 includes promising features, namely vastluy improved emphasis handling, next generation UEB table set and others. at the moment version 3.0.0 has entered alpha testing phase:
https://github.com/liblouis/liblouis/releases/tag/v3.0.0.alpha1

Important things to note:

• A new file named "pattern.c" is introduced that handles various patterns. Without including this file, MS Linker says unresolved symbols.
• We need to test UEB table set to make sure it is more compliant to the standard.
• A lot of testing will be required to make sure braille tables aren't broken and that NVDA can handle them well.

Thanks.