A11Y: Improve readability by adding spacing and focus styles and further suggestions

[peter-neumann-dev]

To resolve issues with readability and focus styles in the backend module, a slight spacing between the selects of the upper form group should be added to prevent overlapping of the existing focus styles from bootstrap.

For inputs and textareas in the translation table, a slight padding and a focus style should be added, to improve readability and identification of the active input. The paddings should be as small as possible to prevent the table from increasing in vertical height.

Additional improvements to consider in the future:

• Add descriptive labels to selects of extension, files, and languages
• Add descriptive labels to inputs inside of translations
• When adding a new row with the ➕ add button, the input for the key of the new row should retrieve focus immediately
• The add, delete and move buttons should be real buttons with a descriptive label
• Allow navigation with arrow keys between cells