implements https://github.com/nim-lang/RFCs/issues/258 (#15503)

* implements https://github.com/nim-lang/RFCs/issues/258

* don't be too strict with custom pragma blocks

* cast pragmas: documentation

* added most missing inference query procs to effecttraits.nim

tests/macros/tgetraiseslist.nim

@@ -1,5 +1,7 @@
 discard """
-  nimout: '''##[ValueError, Gen[string]]##'''
+  nimout: '''##[ValueError, Gen[string]]##
+%%[RootEffect]%%
+true true'''
 """
 
 import macros
@@ -10,13 +12,18 @@ type
     x: T
 
 macro m(call: typed): untyped =
-  echo "##", repr getRaisesList(call), "##"
+  echo "##", repr getRaisesList(call[0]), "##"
+  echo "%%", repr getTagsList(call[0]), "%%"
+  echo isGcSafe(call[0]), " ", hasNoSideEffects(call[0])
   result = call
 
+proc gutenTag() {.tags: RootEffect.} = discard
+
 proc r(inp: int) =
   if inp == 0:
     raise newException(ValueError, "bah")
   elif inp == 1:
     raise newException(Gen[string], "bahB")
+  gutenTag()
 
 m r(2)