build(aio): improve the API Pipe pages (#22702)

This change adds:

* an impure badge for Pipes that are marked as  `pure: false`
* a pipe specific overview that shows the syntax for using a pipe in a template.
* an "input value" section describing the type of the value that the pipe expects.
* a "pipe params" section describing any additional params that a pipe expects.

PR Close #22702

aio/tools/transforms/angular-api-package/processors/extractPipeParams.js

@@ -0,0 +1,19 @@
+module.exports = function extractPipeParams(createDocMessage) {
+  return {
+    $runAfter: ['extractDecoratedClassesProcessor'],
+    $runBefore: ['docs-processed'],
+    $process(docs) {
+      docs.forEach(doc => {
+        if (doc.docType === 'pipe') {
+          const transformFn = doc.members && doc.members.find(member => member.name === 'transform');
+          if (!transformFn) {
+            throw new Error(createDocMessage('Missing `transform` method - pipes must implement PipeTransform interface', doc));
+          }
+          doc.pipeName = doc.pipeOptions.name.replace(/^["']|["']$/g, '');
+          doc.valueParam = transformFn.parameterDocs[0];
+          doc.pipeParams = transformFn.parameterDocs.slice(1);
+        }
+      });
+    }
+  };
+};