feat: have the daemon support multiple manager atSigns

[gkc]

- What I did

• feat: have daemon support multiple manager atSigns
  • made managerAtsign into a list and renamed to managerAtsigns in Sshnpd, SshnpdImpl and SshnpdParams
  • changed the long arg name for the managerAtsigns to managers but preserved manager as an alias
  • modified SshnpdImpl.isFromAuthorizedAtsign accordingly
  • extracted the username sharing code into its own function called from SshnpdImpl.run
  • modified the username and device_info sharing functions to iterate through the manager atSigns and share (or un-share) with each one
• dependency management
  • build: sshnoports: updated dependencies at_onboarding_cli, at_client, at_lookup to latest so no dependency conflicts with latest noports_core which uses at_chops ^2.0.0 and at_commons ^4.0.0
  • build: noports_core: updated at_chops dependency to ^2.0.0
  • build: sshnp_flutter: override at_client_mobile and at_commons dependency versions. Temporary until Need new version of at_client_mobile with at_chops dependency upgraded to ^2.0.0 at_client_sdk#1232 and All widgets need new versions to be published which can use at_commons ^4.0.0 at_widgets#794 have been resolved
• bug fixes
  • fix: set ccd (cached cascade delete) for the username and device_info so that if they are un-shared then their cached copies are deleted from the manager atSigns
  • fix: sshnp client: sshnpd_channel: resolveRemoteUsername was correctly detecting if remote username had not been shared, but was actually returning null rather than (as intended) throwing an SshnpError

[gkc]

@XavierChanth fyi for the c daemon

[cconstab]

Gary works as expected under manual testing.. TY