Standardise the bridge string before converting to bridge emoji pattern

We should standardise the bridge strings before we convert them to bridge emojis (bridgemoji) to better ensure that equivalent bridges have the same representation. We should:

• Strip excess whitespace within the string.
• Re-order the extra bridge parameters in a standard way.

We could either do this when calculating the bridge emojis, or prior to saving the bridge settings.

We should do this in a way that existing bridge's added by the user from our website or other sources are less likely to change.

/cc @morgan @pierov