[Ignore] update CL

cl for v2.2.0-preview.1 (PowerShell#1275)

[Ignore] Rev version to 2.2.0-preview.1 and update CL (PowerShell#1261)

Rev version to v2.1.0-preview.6 and update CHANGELOG (PowerShell#1259)

Rev version to v2.1.0-preview.5 and update CHANGELOG (PowerShell#1256)

Rev version to v2.1.0-preview.4 and update CL (PowerShell#1254)

Rev version to 2.1.0-preview.3 and update CHANGELOG (PowerShell#1249)

Rev version to 2.1.0-preview.3 and update CHANGELOG (PowerShell#1249)

changelog for v2.1.0-preview.1 (PowerShell#1236)

* changelog

* Apply suggestions from code review

Co-Authored-By: Robert Holt <rjmholt@gmail.com>

Co-authored-by: Robert Holt <rjmholt@gmail.com>

Make session-state lock task-reentrant (PowerShell#1217)