Check method input expressions once

If the user mistakenly forgets to wrap their method args in a tuple, then the compiler tries to check that  types within the tuple match the expression args. This means we call `check_expr` once within this diagnostic code, so when we check the expr once again in `demand_compatible`, we attempt to apply expr adjustments twice, leading to ICEs.

This PR attempts to fix this by skipping the expression type check in `demand_compatible` if we have detected an method arg mismatch at all.

This does lead to a single UI test regressing slightly, due to a diagnostic disappearing, though I don't know if it is generally meaningful to even raise an type error after noting that the argument count is incorrect in a function call, since the user might be providing (in-context) meaningless expressions to the wrong method.

I can adjust this to be a bit more targeted (to just skip checking exprs in `demand_compatible` in the tuple case) if this UI test regression is a problem.

fixes #94334
cc #94291

Also drive-by fixup of `.node_type(expr.hir_id)` to `.expr_ty(expr)`, since that method exists.