Unit test: Check if the device can upload

[borgesbruno]

I've wrote some tests for the function that check whether a device can upload. The tests cover many devices through a small list of the user agents.

[johnbillion]

Thanks @borgesbruno.

Can you add an inline comment to each of the datas in the dataProvider stating which browser the user agent refers to? This will make maintenance, debugging, etc easier.

[borgesbruno]

Code refactor, added comments

[borgesbruno]

Hey @johnbillion, tks for the review, it's done ;-)

[johnbillion]

In 36810:

Uploads: Add tests for device upload capabilities based on user agent.

Fixes #35976
Props borgesbruno

[johnbillion]

Tests are failing due to wp_is_mobile() being called indirectly in an earlier test, which sets its $is_mobile static var to false, which causes _device_can_upload() to always return true.

Running the test_device_can_upload() test in isolation succeeds.

The solution is to remove the somewhat pointless static var in wp_is_mobile(), which only serves to avoid a handful of strpos() calls which are fast anyway.

[johnbillion]

In 36813:

Uploads: Remove an unnecessary static var from wp_is_mobile() to allow its direct and indirect use within unit tests. The static `$is_m
obile var was only used to avoid a handful of calls to strpos()`, which are exceptionally fast and result in no measurable increase in
processing time on each call to wp_is_mobile().

See #35976, #20014

[borgesbruno]

Great @johnbillion! Tks for the additional patch