Closes #6539 Update container to v4

[remyperona]

Description

Update the container to version 4, and update the code to match with the upgrade path.

Fixes #6539

Documentation

User documentation

Should have no impact for users.

Technical documentation

Notable changes:

• share() method removed, replaced by addShared()
• Service provider now implements a provides() method

Type of change

• Enhancement (non-breaking change which improves an existing functionality).

New dependencies

• PSR container to v1.1.1 & league container to v4.2

Checklists

Feature validation

• I validated all the Acceptance Criteria. If possible, provide sreenshots or videos.
• I triggered all changed lines of code at least once without new errors/warnings/notices.
• I implemented built-in tests to cover the new/changed code.

Code style

• I wrote self-explanatory code about what it does.
• I wrote comments to explain why it does it.
• I named variables and functions explicitely.
• I protected entry points against unexpected inputs.
• I did not introduce unecessary complexity.