/me slashcommand is no longer working with legacy message parser

Description:

The /me slashcommand is no longer working with legacy message parser. Instead it shows a message with prepending "_ " and appending "_" characters.

Steps to reproduce:

1. Send message /me is testing.

Expected behavior:

It should display a so-called action:

Actual behavior:

Instead it shows a message with prepending "_ " and appending "_" characters.

Problem:

⚠️ The space behind the underscore "_ " at the beginning of the message is breaking it. If I edit and fix that message, it will show correctly. Doing str.substring(1) for params in Rocket.Chat/apps/meteor/app/slashcommands-me/server/me.ts might be all that's needed.

Temporary workaround for users:

When trying to send an action, don't use the /me slashcommand but type it in the correct format to be parsed. No spaces before/after the underscores: _me is testing._
We learn that in Rocket.Chat an action is nothing other than a normal message written in italic.

Server Setup Information:

• Version of Rocket.Chat Server: 5.1.2
• Operating System: Linux
• Deployment Method: Docker
• Number of Running Instances: 1 on this server
• DB Replicaset Oplog: Unknown
• NodeJS Version: v14.19.3
• MongoDB Version: 5.0.12 / wiredTiger (oplog activated)

Client Setup Information

• Desktop App or Browser Version: Chrome 105.0.5195.127
• Operating System: Windows 11 Pro (Version 10.0.22000.1042)

Start in apps/meteor/app/slashcommands-me/server/me.ts and reproduce the issue by sending /me is testing. with the legacy message parser. Inspect how the slash command passes its parameters, then verify that the result renders as an italic action without extra underscore spacing. The issue is old and has had no recent activity, so check for newer related work before starting.