Overhaul javascript organisation, switch to typescript

[mhauru]

This started as an effort to convert all our javascript to typescript. This required restructuring the code a lot, so in the process I also took care of many other long-standing javascript-related issues:

• Modernised how we use the datatables.net library
• Got rid of unnecessary dependencies
• Renamed many of the javascript files to be more helpful
• Oblitared the custom.js file, which included hundreds and hundreds of lines of dead copypasta code from CROP
• Made a bazillion small changes all over, both because they seemed helpful to me, and because the typescript compiler highlighted issues (hurray for type checking catching bugs!)

I appreciate that this is tricky to review since there's so much going on, happy to talk it through. One good bit to read is a new README.md in webapp/base/static, which explains the new organisation of what sort of code should go where.

EDIT: It seems that, very unhelpfully, GitHub does not realise that most of the typescript files are the old javascript files renamed and with small changes, which certainly doesn't make this any easier to review...

[mhauru]

The two failing tests will be fixed by this one: https://github.com/alan-turing-institute/DTBase/pull/180

[EdwinB12]

@GiorgioCerro - Think you might be more suited to reviewing this PR. I'll try and look over it tomorrow but think it would benefit from your review.

@mhauru - I approved and merged #180 , could you merge it into this PR please so the tests pass?

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (305a1fe) 89.19% compared to head (bc36093) 89.19%.

:exclamation: Current head bc36093 differs from pull request most recent head b031913. Consider uploading reports for the commit b031913 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #179 +/- ## ======================================= Coverage 89.19% 89.19% ======================================= Files 75 75 Lines 5036 5036 ======================================= Hits 4492 4492 Misses 544 544 ```

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[GiorgioCerro]

Great work Markus. I will have a deeper look at that either today or tomorrow!

Things to review (mainly):

• README in app/base/statis
• files in backend
• run.sh in webapp

Pull locally and check that nothings breaks.

[GiorgioCerro]

Issues:

• when I run the webapp with DT_CONFIG_MODE="Auto-login" I get 'permission denied' and it doesnt open the page. Without I still get 'permission denied' but I can open the page
• I don't know if it's related, but when I go to the webpage and I create new sensors., I don't see them in the table list (it's empty).
• the password toggle in the user tab doesn't work
• the password toggle in the login doesn't work
• the GetStarted button just after the login, what is that supposed to do? It return a 404. But I guess this is unrelated to this PR.