Implement Wasm validation for known issues/markers (#171)

* Implement Wasm validation for known issues/markers

* Add test for invalid panic import

* Add prefix to error markers

* Add test for ink! codegen error marker

* Implement improved linker error protocol

* Move validation into its own module

* Migrate tests to new linker error protocol

* Fix merge

* Improve code structure

* Fix formatting

* Improve code structure

* Remove mod indirection

* Replace `contains` with `starts_with`

* Add note regarding equivalent ink! type necessity

* Throw an error on invalid import function

* Add sunny day test

* Do not panic if no import section is found

* Update error message on decoding error