Add non-color indicator for links and errors

[hannahackermans]

WCAG Guidelines (this issue crosses several requirements)

Success Criterion 1.3.3 Sensory Characteristics
(Level A)
Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, color, size, visual location, orientation, or sound.

Success Criterion 1.4.1 Use of Color
(Level A)
Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.

Current State of ELMCIP

Hyperlinks to other webpages of ELMCIP and to external websites are indicated only by color unless someone is already focusing on them (hover or keyboard focus). The contrast between the color of hyperlinks and the color of regular text is also very low.
ELMCIP gives an error identification at the top of the page when there are mistakes in filling in a create/edit page. but the field itself is only indicated by making the thin grey line around the field red.

Proposed changes to meet the success criteria

1. Add a non-color indicator for hyperlinks such as underline
2. Increase the contrast between color of regular text and color of hyperlinks (see Increase Contrast #492)
3. add extra identification to errors in forms. For example by adding text into the form itself (not only at the top), or adding an icon to indicate which field has an error etc. See issue Improve Error Idenfication and Error Suggestion #497 for further improvements of error identifications.

[hannahackermans]

I wasn't too happy about requesting to add an underline to all hyperlinks on ELMCIP because there are so many it might influence the readability. However, technique G183 states that "Using a contrast ratio of 3:1 with surrounding text and providing additional visual cues on hover for links or controls where color alone is used to identify" is also "sufficient" to meet the 1.4.1 Use of Color guideline. Please note that the 3:1 is between the linked text and the regular text color, but that both of these colors need a 4.5:1 contrast ration with the background.

This is a webpage with working examples: Links with a 3:1 contrast ratio with surrounding text
Please note that the list of colors on this page would pass if the background is white and the regular text is black. Our background is white, but our regular text is currently grey, so we would either need to find an alternative color or make the regular text darker.