BIQU H2 holder for B1 for print on mirror

Modification of the original model (https://www.thingiverse.com/thing:4757657) for printing on the mirror (or glass).

With the original holder, the extruder carriage struck the clips. Therefore, the extruder mount was moved 7mm lower. The mounting structure has been strengthened.

For mount the fan, I use the model https://www.thingiverse.com/thing:4915655