Feat double puppeting

[dodosan-89]

This pull request includes significant changes to the mautrix-imessage bridge, focusing on improving the bridge's double puppeting capabilities, updating the Dockerfile, and adding a new configuration file. Double puppeting allows a user's Matrix and iMessage accounts to appear as the same user in a bridged room.

Here are the most important changes:

Double Puppeting Improvements:

• config/bridge.go: Added DoublePuppetConfig to the BridgeConfig struct to support double puppeting. Also added GetDoublePuppetConfig() method to return the double puppeting configuration. [1] [2]

• config/config.go: Added CanAutoDoublePuppet() and GetDoublePuppetSecret() methods to the Config struct. These methods check if automatic double puppeting is possible for a given user ID and retrieve the shared secret for double puppeting, respectively.

• config/upgrade.go: Updated the DoUpgrade() function to handle the migration of the double puppeting shared secret map.

• custompuppet.go: Removed unnecessary imports related to double puppeting.

Dockerfile Updates:

• Dockerfile.ci: Commented out the copying and execution of docker-run.sh and example-config.yaml, and added a new entry point and command for mautrix-imessage.

New Configuration File:

• config.yaml: Added a new configuration file for the mautrix-imessage bridge. This file includes various settings for the bridge, such as homeserver details, application service details, iMessage connection config, bridge config, and logging config.

Minor Changes:

• build.sh: Added a line to print the exit status of the go build command.