Add display.proto for API v2

[brentru]

The current Display API (v1) only supports SPI-based displays. Version 2 should extend support to include I2C-connected displays (e.g., SSD1306 OLED, SH1106) which are currently within i2c.proto.

• API should include a .proto file with a .options file
• This should be a new PR, based off the api-v2 branch
• The API should support SPI and I2C displays
• The API should follow naming conventions in API v2 such as:
  • BrokerToDevice message envelope
  • DeviceToBroker message envelope
  • Standardized message names like Add, Remove, Write, etc
    (For reference https://github.com/adafruit/Wippersnapper_Protobuf/blob/api-v2/proto/wippersnapper/analogio.proto)
• The API should come with documentation in the docs folder

[brentru]

Support Qualia/TTL RGB dispalys "because the ESP32-P4 does TTL/MIPI"

[tyeth]

Add the SPI interface, add an interface enum/oneof (see how gps is linked through uart/i2c), refactor deviceType enum, migrate driver + panel to strings, consider the display output/write message_str oneof for future binary+base64 payloads.