process non-language pragma nodes in generics (#24254)

fixes #18649, refs #24183

Same as in #24183 for templates, we now process pragma nodes in generics
so that macro symbols are captured and the pragma arguments are checked,
but ignoring language pragma keywords.

A difference is that we cannot process call nodes as is, we have to
process their children individually so that the early untyped
macro/template instantiation in generics does not kick in.

(cherry picked from commit d72b848d17)

tests/generics/mpragma1.nim

@@ -0,0 +1,3 @@
+macro aMacro*(u:untyped):untyped =
+  echo "in macro"
+  result = u

tests/generics/mpragma2.nim

@@ -0,0 +1,6 @@
+import mpragma1
+proc p*[T]() =
+  proc inner() {.aMacro.} =
+    discard
+  inner()
+  discard

tests/generics/tpragma.nim

@@ -0,0 +1,10 @@
+discard """
+  nimout: '''
+in macro
+'''
+"""
+
+# issue #18649
+
+import mpragma2
+p[string]()