sink parameter inference for types that have destructors (#13544)

* ensure capitalize doesn't take an inferred sink parameter

* sink parameter inference: first version, for now disabled. Changed that sink parameters can be consumed multiple times in order to adhere to our spec.

* sink inference can now be disabled with .nosinks; sometimes for proc type interop this is required

* fixes yet another critical DFA bug

* better implementation that also understands if expressions etc

* document sink parameter inference and allow for global disabling

lib/pure/unicode.nim

@@ -701,7 +701,7 @@ proc capitalize*(s: string): string {.noSideEffect, procvar,
     doAssert capitalize("βeta") == "Βeta"
 
   if len(s) == 0:
-    return s
+    return ""
   var
     rune: Rune
     i = 0

lib/system/assertions.nim

@@ -15,8 +15,10 @@ proc `$`(info: InstantiationInfo): string =
 
 # ---------------------------------------------------------------------------
 
+when not defined(nimHasSinkInference):
+  {.pragma: nosinks.}
 
-proc raiseAssert*(msg: string) {.noinline, noreturn.} =
+proc raiseAssert*(msg: string) {.noinline, noreturn, nosinks.} =
   sysFatal(AssertionError, msg)
 
 proc failedAssertImpl*(msg: string) {.raises: [], tags: [].} =