* AstGen: implement `anyframe_literal` and `anyframe_type`.
 * Introduce `makeSubBlock` to avoid redundant AstGen code for GenZir
   scopes. Allows adding/removing a field without possibility of
   accidentally introducing a bug of forgetting to set the new field.
 * Add to GenZir `nosuspend_node` and `suspend_node` in preparation for
   implementing `suspend` blocks and `nosuspend` blocks.
 * AstGen: fix assembly to support clobbers, multiple outputs, and
   outputs without `->` syntax.
   - `asm` and `asm_volatile` move to `Extended` enum with `small` being
     repurposed for a few things. This frees up 2 ZIR tags, 1 of which
     is used in this commit and 1 is leftover.
 * AstGen: fix `simple_types` incorrectly having multiple conflicting
   values for "undefined" and "null".
   - Also add "anyframe" to `simple_types`.
 * Add `anyframe_type` to type.zig, value.zig and `Zir.Inst.Ref`.
   - Also add i128 and u128 types to `Zir.Inst.Ref` and `simple_types`.
 * Sema/Zir: Fix incorrect math causing the function body to be messed
   up for Extended-encoded functions.
 * Zir: support `i32` fields for "extra" payloads.