Add remaining Zulip user groups

The following are the remaining Zulip user groups that are not yet synced between the team repo and the Zulip instance.

Please review the user groups and send pull requests adding them to the team repo (see below for instructions).

Once these are added, the Zulip user groups will be completely managed by the team repo.

• 'WG-rls2.0' @matklad
• 'WG-llvm' @nagisa
• 'WG-traits' @jackh726 (this group is inactive and only not yet archived due to limitations in the team repo)
• 'project-custom-linter' (this has never been used publicly - perhaps it's inactive?)
• 'WG-polonius' @lqd
• 'WG-rustc-dev-guide' @spastorino https://github.com/rust-lang/team/pull/843
• 'WG-const-eval' https://github.com/rust-lang/team/pull/834
• 'WG-pipelining' (this was last used publicly in Jan 2020 - perhaps it's inactive?)
• 'WG-mir-opt' @oli-obk https://github.com/rust-lang/team/pull/839
• 'mods'
• 'WG-governance' (I believe this working group is inactive)
• 'WG-unsafe-code-guidelines' @RalfJung https://github.com/rust-lang/team/pull/838
• 'WG-ffi-unwind' @BatmanAoD https://github.com/rust-lang/team/pull/845
• 'WG-polymorphization' @davidtwco https://github.com/rust-lang/team/pull/846
• 'WG-self-profile' @wesleywiser
• 'WG-async' https://github.com/rust-lang/team/pull/832
• 'WG-async-sprint-planning' https://github.com/rust-lang/team/pull/832
• 'WG-rfc-2229' (this working group is probably inactive)
• 'WG-diagnostics' @estebank
• 'WG-prioritization/alerts' https://github.com/rust-lang/team/pull/836
• 'project-const-generics' @lcnr
• 'T-compiler/WG-meta' (this group seems to be inactive) https://github.com/rust-lang/team/pull/857
• 'WG-profile-guided-optimization' (this has never been used publicly - perhaps it's inactive?)
• 'WG-nll' (this group is likely inactive) https://github.com/rust-lang/team/pull/856
• 'wg-incr-comp' @pnkfelix
• 'T-community/l10n' (this work is still active in general but not very much on Zulip)
• 'foundation'

Instructions

To add a working group follow the documentation here. More than likely this will simply involve adding the following lines to your team's toml config:

[[zulip-groups]]
name = "T-awesome-zulip-team" # Make sure to change this! 

If you need to add or remove people from the baseline of team membership, you can use the extra-people and excluded-people fields.

If someone you've added does not have a zulip-id field in their personal configuration file, you will need to add it. You can find some instructions on where to find their zulip-id here

As an example, you can see how the compiler team's configuration is set here.

Start with docs/toml-schema.md at the Zulip group instructions and compare the existing teams/compiler.toml configuration. Review the listed unchecked groups and their ownership or activity notes, then inspect the relevant team and personal configuration files, using the README instructions if a zulip-id is missing. Done means the remaining active groups are represented in the team repository and inactive groups have a documented disposition.