Add Color Themes

[diogogmatos]

Added support for color themes across all the pages, including the ability to create a custom theme.

To achieve this:

• Created a new Settings page that can in the future hold other configurations besides themes, like push-notifications, etc.
• Made several changes and adjustments to the way the event colors are applied.
• Used the local storage to save all settings (themes) and as a way to communicate to index.tsx and schedule.tsx the current theming configuration.
• Changed the way the Schedule events are colored, as they now follow whatever colors are set for the events in the Events page. A subject that has a red color in Events will also have a red color in Schedule, and so on. By default, the events are themed by Year (as to distinguish between different years), which means the events in the Schedule page will also be themed by year. Basically, all the coloring is 100% synchronized between the two pages, as to achieve a common theme across the platform.
• A lot of other stuff I don't even remember anymore, I'm open to questions kk.

Additional Improvements:

• Transitioned even more code to Tailwindcss, including the Export and Clear Schedule buttons.
• Added the "Check Indicators" to every Collapse of the filters. There's no easy way to explain this by text, but I basically made it so the tiny blue ball that indicated if you had checkboxes selected inside that collapse will now appear in every collapse, not just the ones immediately before the checkbox. This means that if you have the T1 shift of BD selected, the "2nd year" collapse will have a little indicator that something inside is selected, as well as the "2nd semester" collapse, as well as the "BD" collapse.
• Probably other not visible things.

Note: This is a huge PR so I would appreciate it if you guys tested the hell out of it for bugs because there is a very high chance of those existing, despite all the ones I've already fixed.

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[ruilopesm]

What about adding a reference of this new feature to the README's "Features" section?

[diogogmatos]

What about adding a reference of this new feature to the README's "Features" section?

Done @RuiL1904 ;)

[ruilopesm]

Nevermind this comment 😅