This PR converts everything (aside from electron) from CommonJS to ESM.
It is needed to reduce the changes that will happen during the migration
to Typescript (as TS does not play nice with CJS).

Basically:
- rewrite `require()` to `import`
- rewrite `module.exports` to `exports`
- introduce `ts-node` to run importers so we can convert them to TS too

Lastly, sorry for this larg-ish PR, not my preference but when I tried
to reduce its scope, I would end up with mixed commons/esm that was even
more tricky to handle.

Part 1 of the conversion. Mostly renaming js to ts and making sure
things make still sense. Added also handy TS ESLint rules.

In order to support the various .web/.electron/... I ended up adopting
`index.d.ts` as pattern to share type definition. Let me know if that
makes sense for you too. Right now the function type definition is
duplicated, but the solution will be importing from `index.d.ts` and
using `const fn: FnDef = () => ...` that way we can keep all variants in
sync from a single type file.

Such rewrite however is better done in another PR otherwise we risk
confusing git and loosing history (rename + too many changes). Another
thing that might do in the next PR is convert all files to ESModules, as
things get confusing between CJS exports, ESM default/named and TS adds
extra complains.

Removing
- Debugger
- `perf-deeets`
- `codemirror`

* Dedupe loot-core webpack configs

* Swap to parsing using Peggy

* Actually record syntax errors

* Refactor template types

* Add notifications after applying the templates

* “Successfully”

* Try a Nearley grammar

* Revert "Try a Nearley grammar"

This reverts commit 1e11c07b855a492b905f1291c3eadd93f78ac3de.

Not going with this approach since the error messages are inscrutable.

* switch to PEG.js which has slightly better tooling support

* fix parser

* Fix error reporting

* Adjust grammar for better error messages

Also allow spaces between currency symbol and number

* Fix grammar

* Make #template prefix case insensitive

* Trailing commas

* Remove patch-package from loot-core