Bug 27458: Set focus for cursor to Credit type code field

Bug 27458: Set focus for cursor to Credit type code field

Test Plan:
Before applying patch
1. Click on Administration
2. Scroll down to Accounting and click on Credit types
3. Click New credit type
4. Note how the cursor does not focus on Credit type code field
5. Apply patch
6. Repeat steps 1-3
7. Note how the cursor now focuses on Credity type code field

Signed-off-by: Barbara Johnson <barbara.johnson@bedfordtx.gov>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
JD amended patch: Edit commit title

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>