~ruther/vhdl-i2c

ref: 162bd41ba3de8b24ce8746c8cff37d68445aca88 vhdl-i2c/src d---------
refactor(rx): do not use unnecessary index
chore: use integer instead of natural when with range
fix: make rx properly working
feat: add possibility for 0 delay in delay entity
tests: add startstop condition detector tests, fix behavior
fix: bugs in address detector
fix: compilation errors
feat: add i2c slave state entity
feat: add i2c misc entities
feat: add i2c rx, tx entities
feat: add utility entities

Delay, metastability filter, open drain buffer, synchronous edge detector