Vault 404 error handling needed to be updated since changes related to
exception handling server side.

Also improve returned error messages, add missing test and slightly
refactor tests implementation (use hypothesis instead of harcoded data).

Closes T2388

Previously, a suprising "Error 200" was displayed in place of a message indicating
that the file cannot be rendered.

Also simplify some code in swh.web.tests.data module.

Closes T2389

Naive datetimes are no more allowed in storage API.

That function was missed when moving identifiers related ones in 8b3e0ce5.

Also ensure a content can be successfully browsed from revision view.

Related to T2330

Related to T2330

Related to T2330

Related to T2330

Enable to get SWHIDs context from JavaScript for the currently
browsed object.

Related to T2330

Fix a small regression introduced in 6da9fade and add tests.

Literal date strings must be in ISO 8601 format.

For consistency with other browse views, deprecate the
/browse/directory/(sha1_git)/(path)/ endpoint and add a new one taking
path as query parameter.

Some browse views different from origin context ones can take an
optional 'origin' query parameter name. For consistency whith origin
context views, rename that parameter to 'origin_url'.

Backward compatibility is already ensured in current implementation.

Deprecate all origin context views taking an origin as url argument and add
new views taking the origin url as query parameter.

This change should mitigate double-slash issue that can happen on some clients
or under certain apache2 configuration.

Fix a regression inroduced in 09e18940: when a revision id is null (for
instance when browsing an empty snapshot), do not attempt to lookup revision
data to avoid an error 500.

pytest-django and pytest-flask both declare a fixture named client and
the wrong one is picked when running swh-web tests.

So avoid the loading of pytest flask plugin to prevent errors when
running tests.

Disambiguate and/or deprecate the following browse URLs:

  - GET /browse/origin/(origin_url)/content/(path)/

  - GET /browse/origin/(origin_url)/directory/(path)/

  - GET /browse/origin/(origin_url)/visit/(timestamp)/branches/

  - GET /browse/origin/(origin_url)/visit/(timestamp)/content/(path)/

  - GET /browse/origin/(origin_url)/visit/(timestamp)/directory/(path)/

  - GET /browse/origin/(origin_url)/visit/(timestamp)/log/

  - GET /browse/origin/(origin_url)/visit/(timestamp)/releases/

  - GET /browse/snapshot/(snapshot_id)/content/(path)/

  - GET /browse/snapshot/(snapshot_id)/directory/(path)/

Replace their use by providing timestamp and path as query parameters to these endpoints
for consistency:

  - GET /browse/origin/(origin_url)/content/

  - GET /browse/origin/(origin_url)/directory/

  - GET /browse/origin/(origin_url)/log/

  - GET /browse/origin/(origin_url)/branches/

  - GET /browse/origin/(origin_url)/releases/

  - GET /browse/snapshot/(snapshot_id)/content/

  - GET /browse/snapshot/(snapshot_id)/directory/

Update endpoints documentation to reflect these changes.

Closes T2115
Closes T2135

That message can only be displayed when browsing a directory in a snapshot
context, for instance when browsing a branch whith a non resolvable revision.

Related to T2353

Slightly refactor and improve the swh.web.browse.snapshot_context module:

  - merge _process_snapshot_request function into get_snapshot_context one

  - rename some dict keys and add snapshot / origin related type annotations

  - cleanup and simplify get_snapshot_context implementation

  - update some docstrings

  - add new exhaustive tests for get_snapshot_context function

Closes T2360

When no timestamp or visit id is provided to the get_origin_visit function,
return the first visit with a non null snapshot instead of the first full
visit. Indeed, a partial visit can have a valid snapshot and should be not
filtered out.

Fix the numerous "'WSGIRequest' object has no attribute 'user'" error
reported in production.

Related to T2367

Notably upgrade jQuery to 3.5 and use recommended dompurify option.

Split the test_origin_request_errors pita test into multiple smaller ones,
use hypothesis and remove some no more needed mocks.

Related to T2360

A new major version of MathJax typesetter has been recently released which
now enables to properly bundle the library with webpack.

So remove previous CDN use to get MathJax and use a self hosted version from
now on.

Closes T1680

- reformat the whole swh-web Python codebase using black tool

- add pre-commit hook to run black on all changed files

- update flake8 configuration to match black code style

- remove a lot of useless '# noqa' comments after new formatting

- add black processing in tox

Django 2.2 is now the version used in production so let's gain some tests
execution time by removing the django 1.11 build when using tox.

When an access token has expired, try to perform a silent OIDC session
refresh through the use of a Django middleware.

Closes T2267