chore(rosetta): suppress diagnostics after a certain point (#3158)

In a regular build, Rosetta might throw up hundreds or thousands
of warnings about failed translations. Past a certain point, there's
just no use to so many error messages any more.

Limit the output to 50 at a time.

*"But Rico, why no flag to show them all?"* Well, either a human is
going to actually look at them and fix them, in which case they're
not going to do more than a chunk at a time and re-run Rosetta anyway...
or nobody is going to look at them and then what's the point of
being able to show all? The count is good enough to get a sense for
how bad things are.



---

By submitting this pull request, I confirm that my contribution is made under the terms of the [Apache 2.0 license].

[Apache 2.0 license]: https://www.apache.org/licenses/LICENSE-2.0

packages/jsii-rosetta/lib/util.ts

@@ -12,9 +12,16 @@ export interface File {
 }
 
 export function printDiagnostics(diags: readonly RosettaDiagnostic[], stream: NodeJS.WritableStream) {
-  for (const diag of diags) {
+  // Don't print too much, at some point it just clogs up the log
+  const maxDiags = 50;
+
+  for (const diag of diags.slice(maxDiags)) {
     stream.write(diag.formattedMessage);
   }
+
+  if (diags.length > maxDiags) {
+    stream.write(`(...and ${maxDiags - diags.length} more diagnostics not shown)`);
+  }
 }
 
 export const StrictBrand = 'jsii.strict';