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

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 <[email protected]>
Reviewed-by: Simon Zünd <[email protected]>
Reviewed-by: Danil Somsikov <[email protected]>
Reviewed-by: Ergün Erdoğmuş <[email protected]>
Commit-Queue: Alex Rudenko <[email protected]>

Author: vzaidman

front_end/panels/protocol_monitor/ProtocolMonitor.ts

@@ -291,7 +291,7 @@ 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)  ? '' :