[easee] Add ability to retrieve total consumption per user

[alexf2015]

Description

This adds ability to retrieve total consumption per user.
Changes:

• introduced user thing which has "totalConsumption" channel
• added functionality to poll additional data from additonal API endpoints to populate that channel
• added automatic discovery of users
• adopted documentation
• some minor fixes due to compiler warnings

[Copilot]

Pull request overview

This PR adds support for retrieving total energy consumption per user in the Easee binding. It introduces a new "user" thing type that automatically discovers users with access to an Easee site and polls their consumption data.

Changes:

• Added new user thing type with automatic discovery and a totalConsumption channel
• Refactored common handler functionality into EaseeBaseThingHandler to reduce code duplication
• Enhanced AbstractCommand with improved null safety and generic transform method

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
user-channel-groups.xml	New channel group definition for user consumption tracking
things.xml	Added user thing type configuration with site bridge reference
config.xml	Added user ID configuration parameter
EaseeUserHandler.java	New handler implementing polling for user consumption data
EaseeBaseThingHandler.java	New base class extracting common functionality from handlers
EaseeChargerHandler.java	Refactored to extend base class, removing duplicate code
GetUserTotalConsumption.java	New command to fetch and sum yearly user consumption data
GetSiteUsers.java	New command to fetch site users for discovery
AbstractCommand.java	Enhanced transform method with generics and improved null safety
SiteState.java	Updated to use new transform method signature
EaseeSiteDiscoveryService.java	Added user discovery functionality
EaseeHandlerFactory.java	Added user handler instantiation
EaseeBindingConstants.java	Added constants for user support and API endpoints
README.md	Updated documentation with user thing type details and examples

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[lsiepel]

Looked at all files and came to these comments. But before you look into this, i wonder if adding a new thing user just to have one channel added is the right way.
If i understand it correctly, a site can have multiple users ? And if so, do they all have a different totalConsumption? How does that work?
If there is just one user or multiple users share the same totalConsumption value, i would consider to just add the channel to the site thing.

[alexf2015]

@lsiepel
Implemented changes according to your remarks.

Regarding the general question: A site can have multiple users and totalConsumption is measured for each user differently. There could be more per-user data added in future, e.g.

• last session start date
• last session end date
• last session total energy
• ...

I think with such extensions in mind it makes sense to model it that way. Otherwise the charger will hold all the data and this will soon get confusing.

[lsiepel]

Thanks, LGTM