Bug 19337: Make basic_workflow.t configurable through ENV

Bug 19337: Make basic_workflow.t configurable through ENV

This patch makes the basic_workflow.t selenium tests read ENV for the
following vars:

KOHA_USER
KOHA_PASS
KOHA_INTRANET_URL
SELENIUM_ADDR
SELENIUM_PORT

to properly configure the running environment. If absent, all variables
fallback to current behaviour:

KOHA_USER // 'koha'
KOHA_PASS // 'koha'
KOHA_INTRANET_URL (unchanged)
SELENIUM_ADDR // 'localhost'
SELENIUM_PORT // 4444

[*] Selenium defaults are documented on the Selenium::Remote::Driver docs.

Prerequisites:
Make sure you have a working environment for the Selenium tests:
- Run:
  $ sudo apt update
  $ sudo apt install xvfb firefox-esr

To test:
- Run:
  $ sudo koha-shell kohadev
 k$ cd kohaclone
 k$ wget https://selenium-release.storage.googleapis.com/2.53/selenium-server-standalone-2.53.1.jar \
     -O /tmp/selenium.jar
 k$ SELENIUM_PATH=/tmp/selenium.jar
 k$ Xvfb :1 -screen 0 1024x768x24 2>&1 >/dev/null &
 k$ DISPLAY=:1 java -jar $SELENIUM_PATH &
 k$ prove t/db_dependent/selenium/basic_workflow.t
=> SUCCESS: Tests pass
- Apply this patch
- Run:
 k$ prove t/db_dependent/selenium/basic_workflow.t
=> SUCCESS: Tests pass!
- Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 5bb19808bb23a01a257a0970bd7e2ae43fb5b3d6)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>