Pmtiles js v4 (#499)

* pmtiles js v4: remove pmtiles spec v2 compatibility [#287]
* restructure ts files into src
* add tsup for building ESM/CJS and making types work in ESM
* bump fflate dependency
* update CHANGELOG for js 4.0.0

js/test/index.test.ts

@@ -1,2 +1 @@
-import "./v2.test";
 import "./v3.test";