chore: project structure and deps

[epreston]

Project cleanup before minor revision.

• Update license files for all venders
• Add CI badge
• Organise dependencies
• add standard tool configuration files
• github templates commmon to playcanvas projects

I confirm I have read the contributing guidelines and signed the Contributor License Agreement.

[epreston]

If this is all acceptable, including the CI PR, it would be nice to bump this to 1.0.3 and add a commit to tag it at 1.0.3.

This could be the starting point before major changes to support spine 4.1 on engine 1.65.

[willeastcott]

A note on history. This repo was setup to use Gulp because it was in the days before we adopted Rollup for our standard build system.

[epreston]

We'll make it standard.