Class for cells

[lars-reimann]

Is your feature request related to a problem?

Some operations on tables (e.g. filter_rows) and columns (e.g. all) are dreadfully slow since they are not vectorized.

Desired solution

• Add an abstract class Cell
• Make Row abstract
• Add an implementation of Cell that actually works on an entire column (vectorized)
• Add an implementation of Row that actually works on an entire table (vectorized)
• The cells class can also offer operations like is_missing_value

Possible alternatives (optional)

No response

Screenshots (optional)

No response

Additional Context (optional)

No response

[lars-reimann]

Implemented in #734 and #738.