Mocha v10 requires the lib to be esm compliant.
ESM mandates the use of file extensions in imports, so to minimize the
changes (for now), we rely on the flag `experimental-specifier-resolution=node`
and on `ts-node` (needed only for Node 20).
Breaking changes:
downstream bundlers might be affected by the package.json changes depending on
how they load the library.
NB: legacy package.json entrypoints are still available.
In the lightweight build, lazily load bn.js only when necessary.
Also, use Uint8Arrays instead of strings in PKCS1 padding functions, and
check that the leading zero is present when decoding EME-PKCS1 padding.
