feat: add done fields to tx, rx

chore: get rid of "pulse" from scl names

feat: handle errors in slave state

Moves logic of error handling to slave_state
from tx entity.

feat: handle ack in rx, tx

chore: use process(all) for combinational processes

feat(rx): make rx idle on start/stop condition

fix(rx): stretching behavior

refactor(rx): do not use unnecessary index

fix: make rx properly working

feat: add i2c rx, tx entities