vscode: configure source.organizeImports, disable source.fixAll.ts

[nstepien]

It's basically impossible to find docs on vscode's settings online,
but organizeImports sorts imports (import lines + named imports) and removes unused imports.
I've enabled it so that we can sort named imports on save, until oxfmt handles it.

Caveats:

• It also sorts exports, which may be undesirable.
• It also moves import type {} from 'a'; above import {} from 'a';

Had to save all the files manually to see the impact.

WDYT? I don't mind reverting the import/export orders.
We could live without it.
As I understand it, source.organizeImports merges these two settings into one:

    "source.removeUnusedImports": "explicit",
    "source.sortImports": "explicit"

so we could keep source.removeUnusedImports only.

Also disabled source.fixAll.ts as it's very annoying when vscode removes unreachable code on save when debugging.

https://code.visualstudio.com/docs/typescript/typescript-refactoring#_organize-imports
https://code.visualstudio.com/docs/configure/settings
https://code.visualstudio.com/docs/reference/default-settings

We could also set "allowUnreachableCode": false, in tsconfig.base.json,
so that tsc reports unreachable code as an error.
The default is to report unreachable code in the editor, but not report it when running the tsc cli.
I wonder if it'd help agents if they prioritize TypeScript?

https://www.typescriptlang.org/tsconfig/#allowUnreachableCode