Remove hx4compat stuff (part 1) (HaxeFoundation#11386)

* destroy

* update haxelib submodule

* submodule

* submodule ffs

* cppia

* remove echoServer

* remove more things

* more

* use patched utest for now

* remove one more

* try utest2

* fix test

* explicitly pass `null` to the `type` argument of `utest.Assert.raises()`

* [php] update test HaxeFoundation#9924 for compatibility with the latest utest

* [tests] type-hint Vfs.getContent

* fix Vfs.getContent one more time

* fix display tests

* switch to utest master

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Co-authored-by: Aleksandr Kuzmenko <[email protected]>