chore: format web base code consistently

[dgdavid]

Problem

For whatever reason, the code web frontend code does not have a consistent format.

Solution

Reformat the code with Prettier by running npx prettier . -w after adapting the configuration we had in .prettierrc and updating the list of directories/files it should ignore via .prettierignore file.

We have decided to use as much defaults as possible, ending up with just one override: printWidth. Having lines up to 100 characters length looks a good compromise for us in terms of code readability.

To make the change possible, conflicts between ESLint and Prettier has been solved by making use of https://github.com/prettier/eslint-config-prettier. Something similar with Stylelint, for which https://github.com/prettier/stylelint-prettier has been used.