change min bond to be relative to IRO funds raised in case such exists

[omritoptix]

currently we enfoce 100DYM min bond.
this makes sense for rollapps without IRO or rollapps who raised small amount.
however in case of IRO raising significant funds, this is not enough to prevent attempt of malicious behavior.
We want to change it to be min(IRO_DYM_RAISED/bond_factor, 100DYM) where by default bond_factor = 100.

for example, of IRO_DYM_RAISED = 100kDYM, the min bond will be 1k DYM.
similariliy if IRO_DYM_RAISED = 9KDYM, min bond will be 100DYM.

This bond factor should be a param.

[omritoptix]

updated impl to make the bond per rollapp with enforced min but it can be chosen by rollapp creator