[Proposal] Progress Reporting in Swift Concurrency (#1192)

* ProgressReporter proposal

* reword future directions section + fix typo

* fix spacing

* refactor LocalizedDescriptionOptions

* edit future directions

* update ProgressReporter Pitch to V2

* update proposal to latest version

* fix spacing

* v3 updates

* Update review status for SF-0023 to active review

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Co-authored-by: Charles Hu <[email protected]>

Author: chloe-yeo