[MOV] content/*: move resource files into their related page's directory

Since odoo/documentation#903, the guideline for the location of new
resource (images, downloadable files, RST includes...) files is to place
those inside the directory of the RST page that references them.

For example, if `doc1.rst` has a reference to `image.png` and to
`download.zip`, the file structure should look like this:

├── parent_doc/
│     └── doc1/
│     │     └── image.png
│     │     └── download.zip
│     └── doc1.rst
│     └── doc2.rst
├── parent_doc.rst

Before this commit, most of the resource files were still located inside
'media' directories holding all the resource files referenced by RST
pages located at the same level as these directories. In the example
above, a single 'media' directory would hold all the resource files
referenced by both `doc1.rst` and `doc2.rst`. Doing so prevented us from
figuring out easily which resource file was referenced by which RST page
and, thus, lead to unused resource files piling up in the repository. It
also made it more complicated to define codeowners regex rules because a
team could not simply be assigned to `/some_page.*` but needed to be
assigned to both `/some_page\.rst` and to the location of 'media'.

In order to help new content writers figure out the guideline when
taking examples from other RST pages, this commit retroactively applies
the guideline to existing resource files and 'media' directories. The
left-over resource files that are not referenced by any RST page are
removed.

task-2497965

Part-of: odoo/documentation#2068

content/applications/productivity/discuss/overview/team_communication.rst

@@ -12,7 +12,7 @@ Public and Private channels
 A *Public* channel can be seen by everyone, while a *Private* one is only visible to users invited
 to it.
 
-.. image:: media/create_channel.png
+.. image:: team_communication/create_channel.png
    :align: center
    :height: 370
    :alt: View of discuss’s sidebar and a channel being created in Odo Discuss
@@ -28,7 +28,7 @@ Configuration options
 You can configure a channel’s name, description, email alias, and privacy by clicking on the
 *Channel Settings* icon on the sidebar.
 
-.. image:: media/channel_settings.png
+.. image:: team_communication/channel_settings.png
    :align: center
    :alt: View of a channel’s settings form in Odoo Discuss
 
@@ -41,7 +41,7 @@ Privacy and Members
 | If you choose *Invited people only*, go to the *Members* tab to add your members, or, go to
   Discuss’ main page, select the channel and click on *Invite*.
 
-.. image:: media/invite_channel.png
+.. image:: team_communication/invite_channel.png
    :align: center
    :height: 380
    :alt: View of Discuss’ sidebar emphasizing the option to invite members in Odoo Discuss
@@ -58,7 +58,7 @@ Use a channel as a mailing list
 | Enabling this option allows you to *Moderate this channel*, meaning that messages will need to be
   approved before being sent.
 
-.. image:: media/pending_moderation.png
+.. image:: team_communication/pending_moderation.png
    :align: center
    :alt: View of a message with a pending moderation status in Odoo Discuss
 
@@ -66,13 +66,13 @@ Use a channel as a mailing list
   receive an *Automatic notification*.
 | Mark *Send guidelines to new subscribers* to automatically send instructions to newcomers.
 
-.. image:: media/moderation_settings.png
+.. image:: team_communication/moderation_settings.png
    :align: center
    :alt: View of a channel’s settings form emphasizing the tab moderation in Odoo Discuss
 
 Moderators can: *Accept*, *Reject*, *Discard*, *Always Allow* or *Ban* messages.
 
-.. image:: media/moderate_messages.png
+.. image:: team_communication/moderate_messages.png
    :align: center
    :alt: View of a message to be moderated in Odoo Discuss
 
@@ -83,7 +83,7 @@ Moderators can: *Accept*, *Reject*, *Discard*, *Always Allow* or *Ban* messages.
 Once a channel is moderated, the menu *Ban List* allows you to add email addresses per moderated
 channel to auto-ban them from sending messages.
 
-.. image:: media/ban_list.png
+.. image:: team_communication/ban_list.png
    :align: center
    :alt: View of a channel’s setting form emphasizing the ban Lists menu in Odoo Discuss
 
@@ -94,7 +94,7 @@ Once at least 20 channels, direct message and live chat conversations (if the mo
 on your database) are pinned in the sidebar, a *Quick search…* bar is displayed. It is a clever
 way to filter conversations and quickly find the one you need.
 
-.. image:: media/quick_search.png
+.. image:: team_communication/quick_search.png
    :align: center
    :height: 430
    :alt: View of the Discuss’ sidebar emphasizing the quick search bar in Odoo Discuss
@@ -107,7 +107,7 @@ Finding channels
 | Apply filters criteria and save it for later use. The search function accepts wildcards by using
   the underscore character *(_)* to represent a single character.
 
-.. image:: media/filter.png
+.. image:: team_communication/filter.png
    :align: center
    :alt: View of a channel being searched through filters in Odoo Discuss