DebugInfo: Require a DebugLoc in DIBuilder::insertDeclare()

DebugInfo: Require a DebugLoc in DIBuilder::insertDeclare()

Change `DIBuilder::insertDeclare()` and `insertDbgValueIntrinsic()` to
take an `MDLocation*`/`DebugLoc` parameter which it attaches to the
created intrinsic.  Assert at creation time that the `scope:` field's
subprogram matches the variable's.  There's a matching `clang` commit to
use the API.

The context for this is PR22778, which is removing the `inlinedAt:`
field from `MDLocalVariable`, instead deferring to the `!dbg` location
attached to the debug info intrinsic.  The best way to ensure we always
have a `!dbg` attachment is to require one at creation time.  I'll be
adding verifier checks next, but this API change is the best way to
shake out frontend bugs.

Note: I added an `llvm_unreachable()` in `bindings/go` and passed in
`nullptr` for the `DebugLoc`.  The `llgo` folks will eventually need to
pass a valid `DebugLoc` here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235041 91177308-0d34-0410-b5e6-96231b3b80d8