deftype and defmethod syntax major changes (#3094)

Major change to how `deftype` shows up in our code:
- the decompiler will no longer emit the `offset-assert`,
`method-count-assert`, `size-assert` and `flag-assert` parameters. There
are extremely few cases where having this in the decompiled code is
helpful, as the types there come from `all-types` which already has
those parameters. This also doesn't break type consistency because:
  - the asserts aren't compared.
- the first step of the test uses `all-types`, which has the asserts,
which will throw an error if they're bad.
- the decompiler won't emit the `heap-base` parameter unless necessary
now.
- the decompiler will try its hardest to turn a fixed-offset field into
an `overlay-at` field. It falls back to the old offset if all else
fails.
- `overlay-at` now supports field "dereferencing" to specify the offset
that's within a field that's a structure, e.g.:
```lisp
(deftype foobar (structure)
  ((vec    vector  :inline)
   (flags  int32   :overlay-at (-> vec w))
   )
  )
```
in this structure, the offset of `flags` will be 12 because that is the
final offset of `vec`'s `w` field within this structure.
- **removed ID from all method declarations.** IDs are only ever
automatically assigned now. Fixes #3068.
- added an `:overlay` parameter to method declarations, in order to
declare a new method that goes on top of a previously-defined method.
Syntax is `:overlay <method-name>`. Please do not ever use this.
- added `state-methods` list parameter. This lets you quickly specify a
list of states to be put in the method table. Same syntax as the
`states` list parameter. The decompiler will try to put as many states
in this as it can without messing with the method ID order.

Also changes `defmethod` to make the first type definition (before the
arguments) optional. The type can now be inferred from the first
argument. Fixes #3093.

---------

Co-authored-by: Hat Kid <6624576+Hat-Kid@users.noreply.github.com>

test/decompiler/reference/jak2/engine/util/script-h_REF.gc

@@ -3,21 +3,18 @@
 
 ;; definition of type script-form
 (deftype script-form (structure)
-  ((name symbol                            :offset-assert   0)
-   (spec pair                              :offset-assert   4)
-   (func (function script-context object)  :offset-assert   8)
+  ((name  symbol)
+   (spec  pair)
+   (func  (function script-context object))
    )
   :pack-me
-  :method-count-assert 10
-  :size-assert         #xc
-  :flag-assert         #xa0000000c
   (:methods
-    (script-form-method-9 () none 9)
+    (script-form-method-9 () none)
     )
   )
 
 ;; definition for method 3 of type script-form
-(defmethod inspect script-form ((this script-form))
+(defmethod inspect ((this script-form))
   (when (not this)
     (set! this this)
     (goto cfg-4)
@@ -32,30 +29,27 @@
 
 ;; definition of type script-context
 (deftype script-context (structure)
-  ((load-state   load-state    :offset-assert   0)
-   (key          object        :offset-assert   4)
-   (process      process       :offset-assert   8)
-   (trans        vector        :offset-assert  12)
-   (side-effect? symbol        :offset-assert  16)
-   (got-error?   symbol        :offset-assert  20)
-   (expr         pair          :offset-assert  24)
-   (param-count  int32         :offset-assert  28)
-   (param        object     16 :offset-assert  32)
-   (param-type   object     16 :offset-assert  96)
+  ((load-state    load-state)
+   (key           object)
+   (process       process)
+   (trans         vector)
+   (side-effect?  symbol)
+   (got-error?    symbol)
+   (expr          pair)
+   (param-count   int32)
+   (param         object  16)
+   (param-type    object  16)
    )
-  :method-count-assert 12
-  :size-assert         #xa0
-  :flag-assert         #xc000000a0
   (:methods
-    (new (symbol type object process vector) _type_ 0)
-    (eval! (_type_ pair) object 9)
-    (script-context-method-10 (_type_ object pair) object 10)
-    (script-context-method-11 (_type_ pair pair symbol) symbol 11)
+    (new (symbol type object process vector) _type_)
+    (eval! (_type_ pair) object)
+    (script-context-method-10 (_type_ object pair) object)
+    (script-context-method-11 (_type_ pair pair symbol) symbol)
     )
   )
 
 ;; definition for method 3 of type script-context
-(defmethod inspect script-context ((this script-context))
+(defmethod inspect ((this script-context))
   (when (not this)
     (set! this this)
     (goto cfg-10)