Migrate from ts-jest to @swc/jest

As part of looking into #887 I
ran into a ton of difficulty getting `ts-jest` to work with ESM, with
one of the main issues being related to importing `./utils.js` style
files.

This seems to be an issue with `ts-jest` (or at least the interplay
between `ts-jest` and Jest) and from what I could tell in the issues and
code, this isn't solved yet. The solution to the underlying issue was "fixed"
by suggesting the use of a custom resolver, which is not part of the main
`ts-jest` package (see kulshekhar/ts-jest#1057).

While checking types in the test code is useful, it's not that important
since the actual code is type checked separately (both with the linter
and the compilation steps), and so instead of trying to fix `ts-jest`
and use the custom resolver, I opt for using `@swc/jest` which instead
removes the types entirely.

jest.config.js

@@ -1,6 +1,7 @@
 module.exports = {
   clearMocks: true,
-  preset: "ts-jest",
   testEnvironment: "node",
-  testPathIgnorePatterns: ["/node_modules/", "dist/"],
+  transform: {
+    "^.+\\.(t|j)s?$": "@swc/jest",
+  },
 };