[MLIR][LinAlg] Detensorize interal function control flow.

This patch continues detensorizing implementation by detensoring
internal control flow in functions.

In order to detensorize functions, all the non-entry block's arguments
are detensored and branches between such blocks are properly updated to
reflect the detensored types as well. Function entry block (signature)
is left intact.

This continues work towards handling github/google/iree#1159.

Reviewed By: silvas

Differential Revision: https://reviews.llvm.org/D97148