feat: add memory to app.getAppMetrics() (#18831)

docs/api/structures/memory-info.md

@@ -0,0 +1,9 @@
+# MemoryInfo Object
+
+* `workingSetSize` Integer - The amount of memory currently pinned to actual physical RAM.
+* `peakWorkingSetSize` Integer - The maximum amount of memory that has ever been pinned
+  to actual physical RAM.
+* `privateBytes` Integer (optional) _Windows_ - The amount of memory not shared by other processes, such as
+  JS heap or HTML content.
+
+Note that all statistics are reported in Kilobytes.

docs/api/structures/process-metric.md

@@ -16,6 +16,7 @@
     The time is represented as number of milliseconds since epoch.
     Since the `pid` can be reused after a process dies,
     it is useful to use both the `pid` and the `creationTime` to uniquely identify a process.
+* `memory` [MemoryInfo](memory-info.md) - Memory information for the process.
 * `sandboxed` Boolean (optional) _macOS_ _Windows_ - Whether the process is sandboxed on OS level.
 * `integrityLevel` String (optional) _Windows_ - One of the following values:
   * `untrusted`