[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#2066

content/applications/finance/accounting/bank/reconciliation/use_cases.rst

@@ -18,7 +18,7 @@ Configuration
 No special configuration is necessary to record invoices. All we need
 to do is to install the accounting app.
 
-.. image:: media/use01.png
+.. image:: use_cases/use01.png
    :align: center
 
 Use cases
@@ -39,20 +39,20 @@ customer.
 Our customer send us a payment confirmation. We can thus register a
 payment and mark the invoice as paid.
 
-.. image:: media/use02.png
+.. image:: use_cases/use02.png
    :align: center
 
 By clicking on **register payment,** we are telling Odoo that our
 customer has paid the Invoice. We thus have to specify the amount and the
 payment method.
 
-.. image:: media/use03.png
+.. image:: use_cases/use03.png
    :align: center
 
 Now we can always find the payment details in the Invoice by clicking on the
 :menuselection:`Info --> Open Payment`.
 
-.. image:: media/use04.png
+.. image:: use_cases/use04.png
    :align: center
 
 The invoice has been paid and **the reconciliation has been done
@@ -64,7 +64,7 @@ Case 2: Bank statements reconciliations
 We start at our issued Invoice of 3000 euros for Smith & Co. Let's also
 assume that other Invoices are open for different customers.
 
-.. image:: media/use05.png
+.. image:: use_cases/use05.png
    :align: center
 
 We receive our bank statement and find that not only the invoice issued to Smith & Co has
@@ -73,18 +73,18 @@ been paid, but the one to Buzz of 92 euros as well.
 **Import** or **Create** the bank statements. Please refer to the
 documents from the Bank Feeds section.
 
-.. image:: media/use06.png
+.. image:: use_cases/use06.png
    :align: center
 
 On the dashboard, click on **Reconcile # Items**
 
-.. image:: media/use07.png
+.. image:: use_cases/use07.png
    :align: center
 
 If everything was right (correct partner name, right amount) odoo will
 do the reconciliations **automatically**.
 
-.. image:: media/use08.png
+.. image:: use_cases/use08.png
    :align: center
 
 If some issues are found, you will need to take **manual actions**.
@@ -92,13 +92,13 @@ If some issues are found, you will need to take **manual actions**.
 For example, if the partner is missing from your bank statement, just
 fill it in :
 
-.. image:: media/use09.png
+.. image:: use_cases/use09.png
    :align: center
 
 If the payment is done with a down payment, just check if it is all
 right and validate all related payments :
 
-.. image:: media/use10.png
+.. image:: use_cases/use10.png
    :align: center
 
 .. seealso::