ci: adds Go 1.19.0-rc.2 into matrix (#714)

This adds the 1.19.0-rc2. in the testing matrix.

This also formats the Godocs across the codebase, as
Go 1.19 has started auto-formatting Godoc. https://github.com/tetratelabs/wazero/issues/426

Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>

example_test.go

@@ -8,7 +8,9 @@ import (
 )
 
 // addWasm was generated by the following:
+//
 //	cd examples/basic/testdata/testdata; wat2wasm --debug-names add.wat
+//
 //go:embed examples/basic/testdata/add.wasm
 var addWasm []byte