Autotests: Expand multiple monomers in micromolecules mode

[AlexeyGirin]

Source task(s):

• #5640

• Verify layout adjustments when expanding multiple monomers in a straight chain

• Verify layout adjustments when expanding multiple monomers in a ring structure

• Verify expansion behavior when monomers are connected by multiple bonds

• Verify undo/redo functionality after expanding multiple monomers

• Verify boundary behavior when expanding multiple monomers near canvas edges

• Verify collapse functionality for multiple expanded monomers in chain and ring structures