JS: Deprecate getUnknownMember() and replace its uses with getArrayElement()

Although they mean slightly different things, every single call site
of getUnknownMember() just used it as a way to get array elements.

Since there is no known use-case for the original meaning of
getUnknownMember() I am deprecating it for now.

javascript/ql/lib/semmle/javascript/frameworks/D3.qll

@@ -80,7 +80,7 @@ module D3 {
       or
       this = d3Selection().getMember("node").getReturn().asSource()
       or
-      this = d3Selection().getMember("nodes").getReturn().getUnknownMember().asSource()
+      this = d3Selection().getMember("nodes").getReturn().getArrayElement().asSource()
     }
   }
 

javascript/ql/lib/semmle/javascript/frameworks/Puppeteer.qll

@@ -32,7 +32,7 @@ module Puppeteer {
     or
     result = [browser(), context()].getMember("newPage").getReturn().getPromised()
     or
-    result = [browser(), context()].getMember("pages").getReturn().getPromised().getUnknownMember()
+    result = [browser(), context()].getMember("pages").getReturn().getPromised().getArrayElement()
     or
     result = target().getMember("page").getReturn().getPromised()
   }
@@ -45,7 +45,7 @@ module Puppeteer {
     or
     result = [page(), browser()].getMember("target").getReturn()
     or
-    result = context().getMember("targets").getReturn().getUnknownMember()
+    result = context().getMember("targets").getReturn().getArrayElement()
     or
     result = target().getMember("opener").getReturn()
   }
@@ -58,7 +58,7 @@ module Puppeteer {
     or
     result = [page(), target()].getMember("browserContext").getReturn()
     or
-    result = browser().getMember("browserContexts").getReturn().getUnknownMember()
+    result = browser().getMember("browserContexts").getReturn().getArrayElement()
     or
     result = browser().getMember("createIncognitoBrowserContext").getReturn().getPromised()
     or

javascript/ql/lib/semmle/javascript/frameworks/Vuex.qll

@@ -104,8 +104,7 @@ module Vuex {
       storeName = this.getNamespace() + localName
       or
       // mapGetters(['foo', 'bar'])
-      this.getLastParameter().getUnknownMember().getAValueReachingSink().getStringValue() =
-        localName and
+      this.getLastParameter().getArrayElement().getAValueReachingSink().getStringValue() = localName and
       storeName = this.getNamespace() + localName
       or
       // mapGetters({foo: 'bar'})

javascript/ql/lib/semmle/javascript/frameworks/data/internal/ApiGraphModelsSpecific.qll

@@ -368,7 +368,7 @@ bindingset[pred]
 predicate apiGraphHasEdge(API::Node pred, string path, API::Node succ) {
   exists(string name | succ = pred.getMember(name) and path = "Member[" + name + "]")
   or
-  succ = pred.getUnknownMember() and path = "AnyMember"
+  succ = pred.getUnknownArrayElement() and path = "ArrayElement"
   or
   succ = pred.getInstance() and path = "Instance"
   or