display: Rename display.DisplayBufferRef to display.DisplayRef used by lambda

[ayufan]

What does this implement/fix?

This is a change taken from the #4996.
This requires changes from: #5001.

It is interface breaking change to finish move from display::DisplayBuffer to display::Display:

• this does change lambda: (for display and pages) to be based on display::Display&
• this is breaking change for external display components, as they have to change to use displays.DisplayRef

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other

Test Environment

• ESP32
• ESP32S3
• ESP32 IDF
• ESP8266
• RP2040

Checklist:

• The code change is tested and works locally.
• Tests have been added to verify that the new code works (under tests/ folder).