Core team member guide (#7999)

* copy napari core dev guide

* replace all instance of napari with xarray

* rewrite some napari-specific sentences

* update links in the resources

* list tasks

* fixes

* mention the plan to merge label

Co-authored-by: Michael Niklas  <mick.niklas@gmail.com>

* core dev -> core team member

* choose your own title

* rearrange sections to put tasks before code contributions

* remove dramatic nuclear launch keys analogy

* link to bi-weekly developers meeting

* add more types of tasks

* mention presenting tutorials

* mention representing xarray in user communities

* yet more tasks

* note that you don't have to do everything

* paragraph at top making it clear no extra work is required!

* whatsnew

* add section on issue triage

* Apply suggestions from Deepak's code review

Co-authored-by: Deepak Cherian <dcherian@users.noreply.github.com>

* various fixes

* Update CORE_TEAM_GUIDE.md

Co-authored-by: Joe Hamman <jhamman1@gmail.com>

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* How to run benchmark CI using PR label

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Co-authored-by: Michael Niklas <mick.niklas@gmail.com>
Co-authored-by: Deepak Cherian <dcherian@users.noreply.github.com>
Co-authored-by: Joe Hamman <jhamman1@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>