Bring back form-control-sm

[MewenLeHo]

Prerequisites

• I have searched for duplicate or closed feature requests
• I have read the contributing guidelines

Proposal

According to Cyriaque : "In some exceptional cases we provide components with a lower dont 14 px font size such a Small button or Small quantity selector" :

Therefore we need to put back small inputs (i.e. form controls with CSS class .form-control-sm) into Boosted.

Motivation and context

It will be helpfull to simply use CSS class '.form-control-sm intead of doing weird things like what we have done for the quantity selector (i.e. '$input-padding-y-sm: divide($input-padding-y, 2) !default; // Boosted mod').

[louismaximepiton]

Since the .form-control-sm is back in Boosted, should we try to take a look at this one again ?

[julien-deramond]

Closing it since .form-control-sm is back to Boosted via #1230.
Create a new one to see if using .form-control-sm in our Boosted specific small form controls can be useful.