Supporting conversion of argument attributes along their types.

This fixes a bug: previously, during conversion function argument
attributes were neither beings passed through nor converted. This fix
extends DialectConversion to allow for simultaneous conversion of the
function type and the argument attributes.

This was important when lowering MLIR to LLVM where attribute
information (e.g. noalias) needs to be preserved in MLIR(LLVMDialect).

Longer run it seems reasonable that we want to convert both the
function attribute and its type and the argument attributes, but that
requires a small refactoring in Function.h to aggregate these three
fields in an inner struct, which will require some discussion.

PiperOrigin-RevId: 236709409