src/photos-searchbar.c: Changed ctrl+a behaviour in search

Currently while searching photos by text, hitting the Ctrl+a key will
select all photos that matched the query.

This can lead to unwanted behaviour, like searching for a term then
hitting Ctrl+a Backspace in order to change the query term; this
delete all found images.

To fix this, changed the search bar code for key pressing event in
order to select the text instead of the photos.

GNOME/gnome-photos#124
3 jobs for alter_ctrl_a_behaviour in 23 minutes and 36 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Test
passed #313390
flatpak

00:23:08

 
  Review
passed #313391
review

00:00:28

manual #313392
allowed to fail manual
stop_review