WIP: bit-banging I2C support for EEPROM access on QMOD

for now, it just continuously reads the EEPROM bytes and dumps them to
the serial console for testing.

firmware/src_simtrace/i2c.h

@@ -0,0 +1,5 @@
+#pragma once
+
+void i2c_pin_init(void);
+int eeprom_write_byte(uint8_t slave, uint8_t addr, uint8_t byte);
+int eeprom_read_byte(uint8_t slave, uint8_t addr);