Make the data type conversions more robust by adding some additional type checks

[Guzz-T]

The type for from_heatpump can only be an integer, a list of integers or None. The type for to_heatpump depends on the specific implementation.

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
luxtronik
__main__.py	25	25	0%	3–66
datatypes.py	450	1	99%	147
discover.py	58	1	98%	63
luxtronik/cfi
interface.py	171	3	98%	166–167, 252
luxtronik/scripts
__init__.py	35	5	86%	7–16, 51
discover_shi.py	60	60	0%	8–98
dump_cfi.py	14	6	57%	18–25, 29
dump_shi.py	15	6	60%	21–28, 32
performance_shi.py	63	63	0%	7–89
update_screen.py	105	82	22%	6, 20–41, 46–48, 51–61, 64, 70–75, 78, 81–85, 88–92, 95–97, 100–103, 106–111, 115–116, 119–126, 129–136
watch_cfi.py	32	16	50%	36–47, 50–56, 60
watch_shi.py	33	16	52%	38–49, 52–58, 62
luxtronik/shi
interface.py	320	1	99%	438
TOTAL	2401	285	88%

Tests	Skipped	Failures	Errors	Time
378	0 💤	0 ❌	0 🔥	18.198s ⏱️