[FIX] web_dialog_size: Fix usage for non-admins and reduce calls (#954)

This addon had 2 problems after migrating to v11:

1. One call to backend's `ir.config_parameter.get_param` was done for
   each instantiated dialog, while the setting served for the whole
   session equally.
2. That model is now readable only by admin users, so non-admins
   couldn't use the default at all.

Fixed now.

web_dialog_size/readme/CONFIGURATION.rst

@@ -0,0 +1,3 @@
+By default, the module respects the caller's ``dialog_size`` option.
+If you want to override this and have all dialogs maximized by default,
+set the configuration parameter ``web_dialog_size.default_maximize`` to ``1``.

web_dialog_size/readme/CONTRIBUTORS.rst

@@ -0,0 +1,14 @@
+Contributors
+------------
+
+* Anthony Muschang <anthony.muschang@acsone.eu>
+* Stéphane Bidoul <stephane.bidoul@acsone.eu>
+* Holger Brunn <hbrunn@therp.nl>
+* Siddharth Bhalgami <siddharth.bhalgami@gmail.com>
+* Wolfgang Pichler <wpichler@callino.at>
+* David Vidal <david.vidal@tecnativa.com>
+* Quentin Theuret <quentin.theuret@amaris.com>
+* `Tecnativa <https://www.tecnativa.com>`_:
+
+  * Pedro M. Baeza <pedro.baeza@tecnativa.com>
+  * Jairo Llopis <jairo.llopis@tecnativa.com>

web_dialog_size/readme/DESCRIPTION.rst

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+A module that lets the user expand/restore the dialog box size through a button
+in the upper right corner (imitating most windows managers).
+It also adds draggable support to the dialogs.