[mlir][assemblyFormat] Fix bug when using AttrSizedOperandSegments trait with only...

[mlir][assemblyFormat] Fix bug when using AttrSizedOperandSegments trait with only non-buildable operand types

Summary:
When creating an operation with
* `AttrSizedOperandSegments` trait
* Variadic operands of only non-buildable types
* assemblyFormat to automatically generate the parser
the `builder` local variable is used, but never declared.
This adds a fix as well as a test for this case as existing ones use buildable types only.

Reviewers: rriddle, Kayjukh, grosser

Reviewed By: Kayjukh

Subscribers: mehdi_amini, jpienaar, shauheen, antiagainst, nicolasvasilache, arpith-jacob, mgester, lucyrfox, liufengdb, Joonsoo, grosul1, frgossen, llvm-commits

Tags: #mlir, #llvm

Differential Revision: https://reviews.llvm.org/D79004