pgAdmin 4 commit: 1) Fix network disconnect issue while establishing th

1) Fix network disconnect issue while establishing the connection via SSH Tunnel and it impossible to expand the Servers node. Fixes #4724.
2) Fix server connection drops out issue in query tool. Fixes #4818
3) Fix VPN network disconnect issue where pgAdmin4 hangs on expanding the Servers node. Fixes #4926.
4) Ensure that the Servers collection node should expand independently of server connections. Fixes #4933.

Set the default connection timeout to 10 seconds instead of 0.

Branch
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master

Details
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https://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=4ed2d74d9ca2078a7d93273195edd701459ce551
Author: Aditya Toshniwal <aditya(dot)toshniwal(at)enterprisedb(dot)com>

Modified Files
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docs/en_US/images/server_advanced.png | Bin 42899 -> 56042 bytes
docs/en_US/release_notes_4_16.rst | 4 +
docs/en_US/server_dialog.rst | 3 +-
web/migrations/versions/aff1436e3c8c_.py | 27 ++++
.../browser/server_groups/servers/__init__.py | 96 +++++++++-----
.../server_groups/servers/static/js/server.js | 47 ++++++-
web/pgadmin/browser/utils.py | 9 +-
web/pgadmin/dashboard/static/js/dashboard.js | 10 +-
web/pgadmin/model/__init__.py | 2 +-
web/pgadmin/static/js/sqleditor/execute_query.js | 9 +-
.../js/sqleditor/query_txn_status_constants.js | 11 ++
web/pgadmin/static/js/tree/tree.js | 4 +
web/pgadmin/tools/sqleditor/static/js/sqleditor.js | 8 +-
web/pgadmin/utils/driver/psycopg2/__init__.py | 39 ++++--
.../utils/driver/psycopg2/server_manager.py | 142 ++++++++++-----------
15 files changed, 274 insertions(+), 137 deletions(-)