Fix services' type's isLiteral implementation (#50929)

* fix services' type's isLiteral

* update literal completions tests

* remove booleans from literals

Author: gabritto

src/services/services.ts

@@ -511,7 +511,7 @@ namespace ts {
             return !!(this.flags & TypeFlags.UnionOrIntersection);
         }
         isLiteral(): this is LiteralType {
-            return !!(this.flags & TypeFlags.StringOrNumberLiteral);
+            return !!(this.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral | TypeFlags.BigIntLiteral));
         }
         isStringLiteral(): this is StringLiteralType {
             return !!(this.flags & TypeFlags.StringLiteral);

tests/cases/fourslash/completionsLiterals.ts

@@ -1,6 +1,7 @@
 /// <reference path="fourslash.ts" />
 
 ////const x: 0 | "one" = /**/;
+////const y: 0 | "one" | 1n = /*1*/;
 
 verify.completions({
     marker: "",
@@ -10,3 +11,12 @@ verify.completions({
     ],
     isNewIdentifierLocation: true,
 });
+verify.completions({
+    marker: "1",
+    includes: [
+        { name: "0", kind: "string", text: "0" },
+        { name: '"one"', kind: "string", text: '"one"' },
+        { name: "1n", kind: "string", text: "1n" },
+    ],
+    isNewIdentifierLocation: true,
+});