[mlir] Make locations required when adding/creating block arguments

[mlir] Make locations required when adding/creating block arguments

BlockArguments gained the ability to have locations attached a while ago, but they
have always been optional. This goes against the core tenant of MLIR where location
information is a requirement, so this commit updates the API to require locations.

Fixes #53279

Differential Revision: https://reviews.llvm.org/D117633