[mlir][memref] Fix collapsed shape ops memref.cast folding with changed type

`memref.collapse_shape` has verification logic to make sure
result dim must be static if all the collapsing src dims are static.
Cast folding might add more static information for the src operand
of `memref.collapse_shape` which might change a valid collapsing
operation to be invalid. Add `CollapseShapeOpMemRefCastFolder` pattern
to fix this.

Minor changes to `convertReassociationIndicesToExprs` to use `context`
instead of `builder` to avoid extra steps to construct temporary
builders.

Reviewed By: nicolasvasilache, mravishankar

Differential Revision: https://reviews.llvm.org/D106670