[IMP] base,web_unsplash: Add set up message

Before this commit, There was no Instrustion to Setup this feature like other Integrations.

Now we display message when we enable this feature for the First time from settings.

closes odoo/odoo#44439

Signed-off-by: Romain Derie <rdeodoo@users.noreply.github.com>

addons/base_setup/views/res_config_settings_views.xml

@@ -332,6 +332,9 @@
                                     <div class="text-muted">
                                         Find free high-resolution images from Unsplash
                                     </div>
+                                    <div class="content-group" attrs="{'invisible': [('module_web_unsplash', '=', False)]}" id="web_unsplash_warning">
+                                        <div class="mt16 text-warning"><strong>Save</strong> this page and come back here to set up the feature.</div>
+                                    </div>
                                 </div>
                             </div>
                             <div class="col-12 col-lg-6 o_setting_box" id="base_geolocalize">

addons/web_unsplash/views/res_config_settings_view.xml

@@ -5,7 +5,7 @@
         <field name="model">res.config.settings</field>
         <field name="inherit_id" ref="base_setup.res_config_settings_view_form"/>
         <field name="arch" type="xml">
-            <div id="web_unsplash_settings" position="inside">
+            <div id="web_unsplash_warning" position="replace">
                 <div attrs="{'invisible': [('module_web_unsplash', '=', False)]}">
                     <div class="content-group mt16">
                         <label for="unsplash_access_key" class="o_light_label"/>