feat: add selectFirst method for SpAbstractTextPresenter

[moufort]

Add SelectFirst:ifAbsent: method who select the fist occurence of a String, and do ifAbsent Block when the occurence didn't exist

[estebanlm]

I do no understand why this functionality is needed in the presenter.
Why not just to implement it when, where and how you need it?

In essence, I think this functionality is of higher level of what a text presenter should be... so, not super convinced of integrate this.