More actionable "must have annotation" message (microsoft#35839)

* Give an actionable elaboration.

* Accepted baselines.

* Less words.

* Accepted baselines.

Author: DanielRosenwasser

src/compiler/checker.ts

@@ -19045,7 +19045,7 @@ namespace ts {
                     return getTypeOfSymbol(symbol);
                 }
                 if (diagnostic && symbol.valueDeclaration) {
-                    addRelatedInfo(diagnostic, createDiagnosticForNode(symbol.valueDeclaration, Diagnostics._0_is_declared_here, symbolToString(symbol)));
+                    addRelatedInfo(diagnostic, createDiagnosticForNode(symbol.valueDeclaration, Diagnostics._0_needs_an_explicit_type_annotation, symbolToString(symbol)));
                 }
             }
         }

src/compiler/diagnosticMessages.json

@@ -2851,6 +2851,10 @@
         "category": "Error",
         "code": 2781
     },
+    "'{0}' needs an explicit type annotation.": {
+        "category": "Message",
+        "code": 2782
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",

tests/baselines/reference/assertionTypePredicates1.errors.txt

@@ -184,7 +184,7 @@ tests/cases/conformance/controlFlow/assertionTypePredicates1.ts(149,5): error TS
         assert(typeof x === "string");  // Error
         ~~~~~~
 !!! error TS2775: Assertions require every name in the call target to be declared with an explicit type annotation.
-!!! related TS2728 tests/cases/conformance/controlFlow/assertionTypePredicates1.ts:144:11: 'assert' is declared here.
+!!! related TS2782 tests/cases/conformance/controlFlow/assertionTypePredicates1.ts:144:11: 'assert' needs an explicit type annotation.
         const a = [assert];
         a[0](typeof x === "string");  // Error
         ~~~~
@@ -193,7 +193,7 @@ tests/cases/conformance/controlFlow/assertionTypePredicates1.ts(149,5): error TS
         t1.assert(typeof x === "string");  // Error
         ~~~~~~~~~
 !!! error TS2775: Assertions require every name in the call target to be declared with an explicit type annotation.
-!!! related TS2728 tests/cases/conformance/controlFlow/assertionTypePredicates1.ts:148:11: 't1' is declared here.
+!!! related TS2782 tests/cases/conformance/controlFlow/assertionTypePredicates1.ts:148:11: 't1' needs an explicit type annotation.
         const t2: Test = new Test();
         t2.assert(typeof x === "string");
     }