Add decorator to allow to make all operations fallible (#1190)

Force all operations in the model to be fallible.

When this decorator is applied, operations that do not have a Smithy error attatched, will return Result<OperationOutput, InternalServerError>.

To enable this decorator, create a file called META-INF/service/software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator containing codegen-server/src/main/resources/META-INF/services/software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator.

Closes: #1150
Signed-off-by: Bigo <1781140+crisidev@users.noreply.github.com>