[EPIC] New "Manage accounts" view

[JuancaG05]

We want to make several changes and improvements in the current Manage accounts view, so they will be collected in this epic to track the progress. The related issues are:

• Cookie handling #4227: checking and understanding how cookies are handled in the app, so that it is not an impediment removing the key icon in the Manage accounts view for both accounts with Basic or Bearer authentication
• [FEATURE REQUEST] Make automatic discovery of the account #4301: doing an discovery of the whole account automatically when we login, so that we can remove the sync icon in the Manage accounts view
• [FEATURE REQUEST] Improvements in "Manage accounts" view #4148: removing the sync icon and the key icon safely after the previous issues are completed, fix a glitch for long usernames and unify the behaviour of the app when the cookies/tokens are invalid in Basic and Bearer auth accounts
• [FEATURE REQUEST] New UI for "Manage accounts" view #4312: great improvement in the UI of this view
• [FEATURE REQUEST] Manual removal of local storage #4174: a new icon to clean manually the local storage of the account will be added to the Manage accounts view
• [FEATURE REQUEST] Automatic removal of downloaded files and local storage clean up #4175: to complement the previous issue, an automatic cleaning will be provided as well from settings
• [BUG] "Clear data" button malfunctioning #4309: once both ways of cleaning the app are developed, researching about why the Clear data option from the device settings is not working, and if possible remove this option since we'll already have an option to remove local storage manually
• [BUG] Retried successful uploads don't free space in /tmp folder #4335: problem with the temporary folder, containing uploads that, at least, failed once.

[jesmrec]

Everything done!!