Expand hoisted default params in sem (#15270)

* Expand hoisted default params in sem
Introduce ast.newTree{I,IT}
Add test for default params in procs

* Cleanup

* Simplify hoist transformation and expand test

tests/defaultprocparam/tdefaultprocparam.nim

@@ -1,8 +1,83 @@
 discard """
 output: '''
 hi
+hi
+topLevel|topLevel|
+topLevel2|topLevel2|
+inProc|inProc|
+inProc2|inProc2|
+topLevel|9
+topLevel2|10
+inProc|7
+inProc2|8
+must have been the wind..
+I'm there
+must have been the wind..
+I'm there
+symbol'a'symbol'a'
+symbol'b'symbol'b'
+symbol'a'symbol'b'
+symbol'a'9
+symbol'b'9
+symbol'a'0
 '''
 """
 import mdefaultprocparam
 
 p()
+
+proc testP =
+  p()
+
+testP()
+
+proc p2(s: string, count = s): string = s & count
+
+proc testP2 =
+  echo p2 """inProc|"""
+  echo p2 """inProc2|"""
+
+echo p2 """topLevel|"""
+echo p2 """topLevel2|"""
+
+testP2()
+
+import macros
+macro dTT(a: typed) = echo a.treeRepr
+
+proc p3(s: string, count = len(s)): string = s & $count
+
+proc testP3 =
+  echo p3 """inProc|"""
+  echo p3 """inProc2|"""
+
+echo p3 """topLevel|"""
+echo p3 """topLevel2|"""
+
+testP3()
+
+proc cut(s: string, c = len(s)): string =
+  s[0..<s.len-c]
+
+echo "must have been the wind.." & cut "I'm gone"
+echo cut("I'm gone", 4) & "there"
+
+proc testCut =
+  echo "must have been the wind.." & cut "I'm gone"
+  echo cut("I'm gone", 4) & "there"
+
+testCut()
+
+var a = "symbol'a'"
+var b = "symbol'b'"
+
+block:
+  echo p2(a)
+block:
+  echo p2(b)
+block:
+  echo p2(a, b)
+block:
+  echo p3(a)
+  echo p3(b)
+  echo p3(a, 0)