Configure [`importsNotUsedAsValues`](https://www.typescriptlang.org/tsconfig#importsNotUsedAsValues)
to `error`, and switch from `import` to `import type` where needed.
Also remove the `strict` configuration, as it's inherited from
`@tsconfig/recommended`.
Previously the popup page fetched only the `ruffleEnable` and `ruffleOptout`
options because only those appear in `popup.html`. So the remaining
options were always returned with their default value, making the popup
page think that all tabs need to be reloaded when these options have a
non-default value.
Remove the `keys` parameter of `getOptions`, and instead make it always
return all options. Adapt all usages of `getOptions`, which got simplified
by this change.
In some cases, extension API abstraction objects can be assigned directly
with the equivalent extension API namespace. This reduces much trivial
code that just duplicates all the needed functions.
Also, extract `promisifyStorageArea` to share duplicate code between
the conversions of `chrome.storage.local` and `chrome.storage.sync`
(though `local` is not currently used).
This disallows passing non-existent options:
```ts
utils.getOptions(["doesNotExist"]); // error
```
And also disallows using options that were not requested:
```ts
const options = utils.getOptions(["ruffleEnable"]);
options.ignoreOptout; // error
```
relrelb