UPM Package and Unity update

[orenw-resonai]

A number of changes:

• Update to Unity 2019.4.7f1.
• Remove the need for custom WebGLTemplate or editing the index.html file.
• Improvements in JS and C# interoperability.
• UPM package instead of an Assets folder in a project.
• 2 components(UGUIWebGLInputField and TMPWebGLInputField) for input detection.

Might be easier to look on this PR by the commit changes.