[DevTools][Protocol Manager] Fixed Protocol Manager displaying events with no params as "(pending)". (#200)

CDP events pending doesn't make sense, since events can't be updated
after they arrive (since they don't have an id anyway):
https://github.com/ChromeDevTools/devtools-frontend/blob/3201a3630665afd30e0a879f4ebeae6fcc4f3806/front_end/panels/protocol_monitor/ProtocolMonitor.ts#L562-L587

Also, events are allowed to have no params based on:
* JSON-RPC 2.0 Specification: https://www.jsonrpc.org/specification#:~:text=This%20member%20MAY%20be%20omitted
* and CDP Wire Format: https://chromium.googlesource.com/chromium/src/+/master/third_party/blink/public/devtools_protocol/#:~:text=CDP%20is%20designed%20with%20JSON%2DRPC%202.0%20as%20the%20primary%20wire%20format

The two events that caught my eye are:
* Debugger.resumed
https://chromedevtools.github.io/devtools-protocol/tot/Debugger/#event-resumed
* and Runtime.executionContextsCleared
https://chromedevtools.github.io/devtools-protocol/tot/Runtime/#event-executionContextsCleared

Both are expected to be sent without params, however Chrome does send an
empty object params for them.

I work on the DevTools branch for React Native-
https://github.com/facebook/react-native-devtools-frontend

We've omitted "params" for these events as per the CDP docs, resulting
in "(pending)" displayed in the Protocol Monitor. We thought we made a
mistake at first, but it turns out it's just the Protocol Monitor's UI.

Screenshots of the issue and the fix are attached in
https://issues.chromium.org/issues/440012466.

Fixed: 440012466
Change-Id: I34e2472287d66b7cbe9146deae27fac138535425
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6862800
Reviewed-by: Alex Rudenko <alexrudenko@chromium.org>
Reviewed-by: Simon Zünd <szuend@chromium.org>
Reviewed-by: Danil Somsikov <dsv@chromium.org>
Reviewed-by: Ergün Erdoğmuş <ergunsh@chromium.org>
Commit-Queue: Alex Rudenko <alexrudenko@chromium.org>

Author: vzaidman

front_end/panels/protocol_monitor/ProtocolMonitor.ts

@@ -277,7 +277,7 @@ export const DEFAULT_VIEW: View = (input, output, target) => {
                         <td>
                           ${message.result    ? html`<code>${JSON.stringify(message.result)}</code>` :
                                 message.error ? html`<code>${JSON.stringify(message.error)}</code>` :
-                                                '(pending)'}
+                              'id' in message ? '(pending)' : ''}
                         </td>
                         <td data-value=${message.elapsedTime || 0}>
                           ${!('id' in message)  ? '' :