[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/finance/accounting/fiscal_localizations/localizations/australia.rst

@@ -18,19 +18,19 @@ Configuration Steps
 #. Check that the Australian localization module (Australia - Accounting) is installed.
 #. Configure the *KeyPay API*.
 
-   .. image:: media/australia-keypay-api.png
+   .. image:: australia/australia-keypay-api.png
       :align: center
       :alt: Odoo Accounting settings includes a section for the Australian Loclization
 
 #. More fields become visible after clicking on *Enable KeyPay Integration*.
 
-   .. image:: media/australia-keypay-integration.png
+   .. image:: australia/australia-keypay-integration.png
       :align: center
       :alt: Enabling KeyPay Integration in Odoo Accounting displays new fields in the settings
 
 #. You can find the API Key in the *My Account* section of the KeyPay platform.
 
-   .. image:: media/australia-keypay-myaccount.png
+   .. image:: australia/australia-keypay-myaccount.png
       :align: center
       :alt: "Account Details" section on the KeyPay dashboard
 
@@ -38,7 +38,7 @@ Configuration Steps
    change it.*
 #. You can find the **Business ID** in the KeyPay URL. (i.e., ``189241``)
 
-   .. image:: media/australia-keypay-business-id.png
+   .. image:: australia/australia-keypay-business-id.png
       :align: center
       :alt: The KeyPay "Business ID" number is in the URL
 
@@ -51,14 +51,14 @@ The API syncs the journal entries from KeyPay to Odoo and leaves them in draft m
 includes the KeyPay payslip entry ID in brackets for the user to easily retrieve the same record in
 KeyPay and Odoo.
 
-.. image:: media/australia-keypay-journal-entry.png
+.. image:: australia/australia-keypay-journal-entry.png
    :align: center
    :alt: Example of a KeyPay Journal Entry in Odoo Accounting (Australia)
 
 .. note::
    The API sync is triggered by scheduled actions.
 
-   .. image:: media/australia-keypay-scheduled-actions.png
+   .. image:: australia/australia-keypay-scheduled-actions.png
       :align: center
       :alt: Scheduled Actions settings for KeyPay Payroll in Odoo (debug mode)
 
@@ -67,7 +67,7 @@ Odoo).
 
 The accounts used by KeyPay are defined in the section **Payroll settings**.
 
-.. image:: media/australia-keypay-chart-of-accounts.png
+.. image:: australia/australia-keypay-chart-of-accounts.png
    :align: center
    :alt: Chart of Accounts menu in KeyPay