Add community team alumni

[dtolnay]

Citations:

community-localization
#22

community-survey
rust-lang/www.rust-lang.org@e34026e, see src/data/teams/community/teams/survey.yml. Note for now I am only backfilling alumni who already have a profile in the people directory of this repo from some other team membership, i.e. not mgattozzi in this case. We can pursue those cases separately but I figure it would require pinging and getting explicit approval from such contributors to be added into a dataset / website they are not already in, as it's not free: for example they'd become obligated to update this data in the event of name changes.

community
rust-lang/prev.rust-lang.org#155 + rust-lang/prev.rust-lang.org#328 + rust-lang/prev.rust-lang.org#458

See also relevant discussion in rust-lang/prev.rust-lang.org#1098. The old community team rosters are really "Community team (including subteams)". Based on this, I have avoided importing alumni from the prev.rust-lang.org community team roster for whom both of the following are true:

1. currently already alumni or active members of a current community subteam; and

2. not listed as a community team members post-split of the community team into subteams in 895daaf, in which the community team changes were sourced from Governance Page www.rust-lang.org#271.

This applies to:

• arshiamufti (community-rustbridge)
• celaus (community-events)
• flaki (community-events)
• mattgathu (community-events, community-rustbridge)
• spacekookie (community-rustbridge)
• wezm (community-content)