Climate/Daikin - support also 0.5C temperature steps

**Describe the problem you have/What new integration you would like**

Currently, daikin ir remote only allows setting target temperatures in 1.0C steps (refer to daikin.h). My Daikin unit's remote does 0.5C steps. ESPHome is ignoring 0.5C increments (ignoring the last bit of the temperature field), so when I set to '22.5C' on the remote, ESPHome is updating state to '22C'.

Suggest adding a config line for daikin climate "halfdegree: true", which then:
(a) inits the ir climate with 0.5 degree increments instead of 1.0 degree increments
(b) receiver reads the last bit of the temp field and sets the 0.5C correctly
(c) transmitter sends the 0.5C bit
For users with whole-degree remotes/units, they can leave the setting out (default false).

**Please describe your use case for this integration and alternatives you've tried:**

To work with my air conditioner / support more seamless operation with remote.
Alternatives: none available. Not sure whether the custom climate could be used to create this situation.

**Additional context**

Start by reading daikin.h and trace how ESPHome initializes the Daikin climate, receives the temperature field, and transmits it. The work is complete when an optional halfdegree setting enables 0.5C initialization, preserves the last temperature bit on reception, and transmits it, while the default continues to support whole-degree units.

Written by the indexing model from the issue text.