Bug 28853: Fix authority plugin when textarea in biblio record editor

Bug 28853: Fix authority plugin when textarea in biblio record editor

In biblio record editor, when subfield value contains more than 100 characters the editor uses a textarea instead of an input.
On a field using authority plugin, this breaks the JavaScript because it only searches for input tags :
In /koha-tmpl/intranet-tmpl/prog/en/modules/authorities/blinddetail-biblio-search.tt :
> this.getElementsByTagName('input')[1].value = values[i];

Test plan :
1) Prepare :
1.1) Create a new biblio record with a field using authority plugin, for example 606
1.2) Do not use authority plugin but enter in 606$x more than 100 chars
1.3) Save record
1.4) Create a new autority for 606 biblio field with $a and a $x containing more than 100 chars
2) Test 1 :
2.1) Edit again the biblio record, you see a text area for 606$x
2.2) Use authority plugin on field 606
2.3) Search and choose the new autority
2.4) Check $a,$x and $9 are well filled
3) Test 2 :
3.1) Empty field 606
3.2) Create a second $x subfield and fill it with a random value
3.3) Use authority plugin again on field 606
3.4) Search and choose the new autority
3.5) Check $a and $9 are well filled
3.6) Check first $x contains the value from autority and second $x is empty

Signed-off-by: Florian Bontemps <florian.bontemps@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>