~ruther/vhdl-i2c

ref: fa24a4372ede12873e8e43a3153b19696f667b81 vhdl-i2c/src/i2c d---------
chore: use process(all) for combinational processes
fix: tx bugs
feat(rx): make rx idle on start/stop condition
fix(rx): stretching behavior
refactor(rx): do not use unnecessary index
chore: use integer instead of natural when with range
fix: make rx properly working
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