Implement a "File viewer" extension point

[Nicklas Nordborg]

Some files that are stored/produced in BASE contain data that it could be interesting to visualize using an extension mechanism. In a way this can be implemented already with the "ListColumn" and "Toolbar" extension points but it requires that the user navigates to the "File manager".

The idea with a "File viewer" is that is should be possible to include in other places as well. For example, in the "Data files" and "Other items related to..." lists that can be found on regular item pages.

We could for example extend the "View" and "Download" icons with more actions.

[Nicklas Nordborg]

In 7756:

References #2199: Implement a "File viewer" extension point

Defined the 'net.sf.basedb.clients.web.file-viewer' extension point. It re-uses the ButtonAction interface to specify action. Information about the current item need more than just the file so the FileViewerContext class was created that can also hold more information about files that are attached or linked to a parent item.

[Nicklas Nordborg]

In 7757:

References #2199: Implement a "File viewer" extension point

Started to re-implement the "View" and "Download" actions as extensions.

[Nicklas Nordborg]

In 7758:

References #2199: Implement a "File viewer" extension point

Implemented functioanlity for easier handling of dynamic attributes to all action implementations that are subclasses to DynamicActionAttributeSupport. This includes the ButtonBean implementation that is used by the file view/download actions.

[Nicklas Nordborg]

In 7759:

References #2199: Implement a "File viewer" extension point

Added support for changing the HTML tag used by the CompactButtonRenderer. The default value is <a>.

The file action extension point now uses <span> instead.

Added some styling and changed the Base.getFileLinks() method to use the same HTML structure.

[Nicklas Nordborg]

In 7760:

References #2199: Implement a "File viewer" extension point

Implemented in the file manger list and single-item pages.

[Nicklas Nordborg]

In 7761:

References #2199: Implement a "File viewer" extension point

Implemented in the any-to-any lists.

[Nicklas Nordborg]

In 7762:

References #2199: Implement a "File viewer" extension point

Implemented in the item overview.