Pending accessibility issues

[Mil4n0r]

Related to #1899.

There are some issues that have been added as exception rules but have to be addressed at some point. I am putting the list here:

• Currently, a default alt text has been put inside the Card component image in order to meet the WCAG standards. It should be customizable using a component prop. NOTE: The Card component is planned to be reworked, so the problem should be addressed once this is done.

• The tabIndex is not being correctly used inside the Chip component, potentially causing a problem with the focus of the component. NOTE: This componente is planned to be reworked as well, so the problem should be adressed once this is done.

• There are currently multiple problems regarding color-contrast.

• Chip - Chromatic -> color-contrast

• Date Input - Chromatic -> color-contrast

• Date Input - Date Picker States -> color-contrast

• File Input -> color-contrast

• Footer -> color-contrast

• NumberInput -> color-contrast

• RadioGroup -> color-contrast

• StatusLight -> color-contrast

• Tabs -> color-contrast

• TextInput -> color-contrast

• Textarea -> color-contrast

• Toggle Group -> color-contrast
  NOTE: Most of those issues are caused by text that is disabled. WCAG 2.0 defines four types of "incidental" text that are not required to meet the contrast requirements, one of them being disabled text, so adding the aria-disabled="true" tag to these componentes should be enough. However, there are other cases that have to be adressed (such as Calendar previous and next month days being too light or StatusLight colors)

• DateInput and Select have accessibility problems regarding keyboard interaction and nested interaction respectively. They require deeper understanding on what should be expected from the components and will require some extra work.