Consider renaming serverReadyAction -> onServerReady

[isidorn]

Refs: #69313

Just personal preference, but I prefer onServerReady since it sounds more like what it does -> that we actually do something when the server is ready.

[isidorn]

Also consider renaming pattern to portPattern since the pattern property only captures the port looking at the description.
Unless there are plans in the future to extend this property to more.

[isidorn]

Also consider to change openExternally to openExternal since that is the name that we use in our vscode.d.ts https://github.com/Microsoft/vscode/blob/393b48d4a5de85b6fa1d2ad0a59588d6715e12ea/src/vs/vscode.d.ts#L5969

[weinand]

• I prefer serverReadyAction over onServerReady because most users are not used to the VS Code naming conventions. In addition serverReadyAction sets a context for the action attribute that follows.
• pattern: No, the pattern covers both ports or URIs.
• openExternally: end user features don't have to match grammatically incorrect developer API names (and most users are not VS Code extension developers).