Fix Buffer.toString encoding to match Node.js

[prydt]

Current implementation of Buffer.toString does not match Node.js behavior when using undefined as encoding.

Folks have run into this here: mariadb-corporation/mariadb-connector-nodejs#322 (comment)

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[prydt]

I have read the CLA Document and I hereby sign the CLA

[anonrig]

Can you add a test?

[prydt]

Can you add a test?

Added a test. My initial thought was to reuse normalizeEncoding but found that Buffer.toString should fail on null while streams which were using the same encoding function accept null as well (readable_setencoding_null), so I went back to using getEncodingOps but adding a special case for undefined.

[anonrig]

We don't allow fix ups. Can you squash all your commits?

[prydt]

We don't allow fix ups. Can you squash all your commits?

Done. Thank you both!

[anonrig]

Eslint tests are failing.

[prydt]

Eslint tests are failing.

/root/.cache/bazel/_bazel_root/ebde65d3f8fba119063dd4cdef01aad0/sandbox/processwrapper-sandbox/176/execroot/_main/bazel-out/aarch64-fastbuild/bin/src/node/node@eslint_/node@eslint.runfiles/_main/src/node/internal/internal_utils.ts
   54:3   error  'enc' may use Object's default stringification format ('[object Object]') when stringified  @typescript-eslint/no-base-to-string
   60:16  error  'enc' may use Object's default stringification format ('[object Object]') when stringified  @typescript-eslint/no-base-to-string
   65:48  error  'enc' may use Object's default stringification format ('[object Object]') when stringified  @typescript-eslint/no-base-to-string
   75:16  error  'enc' may use Object's default stringification format ('[object Object]') when stringified  @typescript-eslint/no-base-to-string
   85:16  error  'enc' may use Object's default stringification format ('[object Object]') when stringified  @typescript-eslint/no-base-to-string
   93:12  error  'enc' may use Object's default stringification format ('[object Object]') when stringified  @typescript-eslint/no-base-to-string
  102:12  error  'enc' may use Object's default stringification format ('[object Object]') when stringified  @typescript-eslint/no-base-to-string
  111:12  error  'enc' may use Object's default stringification format ('[object Object]') when stringified  @typescript-eslint/no-base-to-string

When looking at the lint failures, it looks like it has to do with lines that I didn't touch within getEncodingOps. Should I change this other code to pass the lint or should I add enable / disable eslint comments? This function already disables certain lints.

[prydt]

I've added a fix for the lint, and it passes tests locally. Just put in a separate commit to make it easy to review since I'm not certain about why the code I'm modifying was written like this in the first place.

Will squash if you are okay with this approach.

[prydt]

Should be squashed and ready.