feat(plg): remove seats from subscription

[taras-yemets]

Closes https://github.com/sourcegraph/sourcegraph/issues/63234
Design

Adds a button to remove the remaining invites from a subscription.

Screen.Recording.2024-06-21.at.01.20.23.mov

Known deviation from design (cc: @rrhyne)

The “Remove User” success message and the “Remove Seats from Subscription” alerts are positioned differently than in the design. The “Remove User” banner, along with other user and invite list alerts, is placed above the users list, below the page title or the invites textbox if rendered. The “Remove Seats from Subscription” banner, along with other invite textbox alerts, is located above the invites textbox instead of above the page title and all the page content. These issues will be addressed in follow-up PRs, as we need to refactor the existing Team Members page layout.
Created an issue to address it:

• https://github.com/sourcegraph/sourcegraph/issues/63411

Test plan

• Run a Sourcegraph instance in dotcom mode
• Sign in as a team admin
• Ensure there are free seats on your team (invites remaining)
• Ensure "Remove invites from plan" button is rendered
• Check the number of invites remaining
• Click the button
• Ensure the subscription has been updated and now the max seats reduced by the number of remaining invites
• Ensure the success banner is rendered

Changelog

[chrsmith]

The code changes looks good. But I'm not sure about the UI design here. (But will defer to Rob, and admit I haven't been following the specific threads/follow ups closely.)

But it just seems a little unexpected to have a "remove all unused seats" button, which will have implications on the billing. (Since if the admin were to immediately "add one more seat" they would need to pay for that, even though they just got done removing that seat.)

So I would expect a more "heavyweight" sort of "+ / - button" approach, and have this on the modify Team Seats page. (But perhaps that's already the plan. Or we have good reason to go with this approach.)

[chrsmith]

Just to confirm, if there are "no unfilled seats" this element won't be visible at all right? (Since, it wouldn't make sense to offer the user to send invites to fill seats that don't exist?)

[taras-yemets]

Exactly! We have the remaining seat count check a few lines higher
https://github.com/sourcegraph/sourcegraph/blob/d3152ac5d3df86a55c364d201727314058d0f4d4/client/web/src/cody/invites/InviteUsers.tsx#L119-L121

[taras-yemets]

But it just seems a little unexpected to have a "remove all unused seats" button, which will have implications on the billing. (Since if the admin were to immediately "add one more seat" they would need to pay for that, even though they just got done removing that seat.)

I agree with this concern. We need to be more explicit about what exactly is going to happen when we free N seats and then suddenly want them back in the next moment.
cc: @rrhyne.

[taras-yemets]

@chrsmith, @rrhyne, I'm going to merge it as it is and iterate in the follow-up PRs.

[rrhyne]

Thanks Taras... good call merging early. Would definitely like consistency on where banners are displayed.

This all worked really well in my testing.