Make asdict support thrift types, and add asthrift, and asjson

Summary: This change is so that we can deprecate `//torchx/fb/util:thrift_py3` in favor of the `torchx.specs.fb.serde` module

Reviewed By: ethanbwaite

Differential Revision: D87121675

Author: kiukchung

.flake8

@@ -4,7 +4,7 @@ max-line-length = 120
 # C408 ignored because we like the dict keyword argument syntax
 # E501 is not flexible enough, we're using B950 instead
 ignore =
-    E203,E305,E402,E501,E721,E741,F405,F821,F841,F999,W503,W504,C408,E302,W291,E303,
+    E203,E305,E402,E501,E704,E721,E741,F405,F821,F841,F999,W503,W504,C408,E302,W291,E303,
     # shebang has extra meaning in fbcode lints, so I think it's not worth trying
     # to line this up with executable bit
     EXE001,