Refactor AdcMethod + ISR(1)-d

[frieschneider]

Refactor AdcMethod.py:

• explicitly differentiate between ADC calculation (AdcMethod) and property calculation (IsrMethod)
• method validation does not rely anymore on creating a list with all valid methods
• added some minimal tests

Include ISR(1)-d:

densities:

• reorganized different terms
• used already available check_doubles_amplitudes function to assess whether doubles excitation are present (this function throws a ValueError -> try except layout)
• renaming of the functions (e.g. s2s_tdm_adc2 is now called s2s_tdm_isr2)

Modified transition moments and B matrix:

• ISR(1)-d B matrix: block_orders need to be explicitly set. Update _default_block_orders?
• renaming (adc -> isr)

no test yet for ISR(1)-d

[jonasleitner]

Should this function call isr1s to avoid the repetition for the first-order singles-singles contribution?

[jonasleitner]

Suggested change

	def _default_block_orders(cls,
	method: Method
	) -> dict[str, int]:
	def _default_block_orders(cls, method: Method) -> dict[str, int]:

[jonasleitner]

Suggested change

	def _base_method(self) -> str:
	return self._method_base_name + self.level.to_str()
	def _base_method(self) -> str:
	assert self._method_base_name is not None
	return self._method_base_name + self.level.to_str()

[jonasleitner]

I think it would be good to add a comment for each special level that explains what the level means

[jonasleitner]

I think we also need to verify that split is at most of length 1 with cvs being the only valid entry, right?

Suggested change

	if split and split[0] not in ["cvs"]:
	raise ValueError(f"{split[0]} is not a valid method prefix")
	valid_prefixes: tuple[str, ...] = ("cvs",)
	if len(split) > len(valid_prefixes):
	raise ValueError(f"Invalid number of method prefixes provided in {split}.")
	if any(pref not in valid_prefixes for pref in split):
	raise ValueError(f"Invalid method prefix in {split}.")

[jonasleitner]

Suggested change

	if isinstance(level.value, int):
	if level.value <= self.max_level:
	return
	if isinstance(level.value, int) and level.value <= self.max_level:
	return