[Proposal] ProgressManager: ProgressReporting in Swift Concurrency (swiftlang#1307)

* 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

* Round 2 Pitch

* fix typo

* update proposal to v5

* add code documentation

* Update status for SF-0023 to 2nd Review

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

Author: 3 people