enable updates to `sample_id`

[keviny2]

updates to sample_id must be reflected in both img_data and column_data. Bioconductor already handles this nicely, ensuring imgData and colData are updated simultaneously:

spe$sample_id <- paste(spe$sample_id, "A", sep=".")

will likely need column validators in BiocFrame

class BiocFrame:
 def add_validator(self, column: str, validator_func):
 self._validators[column] = validator_func
 
 def __setitem__(self, key, value):
 if key in self._validators:
 self._validators[key](value) # trigger sync between img_data/column_data

this would let SpatialExperiment register a validator to keep both data structures in sync when sample_id changes.

[jkanche]

I do like the idea of streamlining this. My only suggestion would be to name the function more explicitly, something like add_column_validator or register_column_validator