pgAdmin 4 commit: Improve code coverage and API test cases for Server m

Improve code coverage and API test cases for Server module. Fixes #5319

Branch
------
master

Details
-------
https://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=f0c86741a4efacc300bdb7d5c85a07e7ad0933a3
Author: Rahul Shirsat <rahul.shirsat@enterprisedb.com>

Modified Files
--------------
docs/en_US/release_notes_5_2.rst                   |   1 +
.../browser/server_groups/servers/__init__.py      |   9 +-
.../servers/tests/servers_test_data.json           | 384 ++++++++++++++++++++-
.../server_groups/servers/tests/test_add_server.py |  24 ++
.../servers/tests/test_check_connect.py            |  88 ++++-
.../servers/tests/test_check_recovery_code.py      |  63 ++++
.../servers/tests/test_check_ssh_mock_connect.py   |  99 ++++++
.../servers/tests/test_password_change.py          | 104 ++++++
.../tests/servers_group_test_data.json             |  45 +++
.../tests/test_servers_groups_childrens.py         |  84 +++++
.../browser/server_groups/tests/test_sg_get.py     |   8 +-
web/pgadmin/browser/server_groups/tests/utils.py   |  16 +
12 files changed, 893 insertions(+), 32 deletions(-)