Add SP Siteusers addById() method

[RoelVB]

Category

• Bug fix?
• New feature?
• New sample?
• Documentation update?

What's in this Pull Request?

This PR adds the addUserById() method to be able to add siteusers using their ID.

[patrick-rodgers]

Hey, what does this do? Doesn't the user id come from when you add the user to the site? Can you help us understand what this update is for?

[RoelVB]

We have removeById() and removeByLoginName(), but for some reason for adding we only had a method for using the loginname.
This PR adds the option be able to also add users by their ID.

[RoelVB]

I now understand why this PR is confusing. This same method is used by site-groups here:

pnpjs/packages/sp/site-groups/types.ts

Lines 70 to 72 in 73889b4

	public get users(): ISiteUsers {
	return SiteUsers(this, "users");
	}

In that context the method makes sense, but it doesn't for siteusers.

[juliemturner]

So I think we're just going to close this as I don't think it's needed.