std/io/bufio - Parameterize input TextEncoder in readLines and readStringDelim

[carragom]

Here is an attempt to implement what is proposed on #920, please let me know what you think.

[CLAassistant]

All committers have signed the CLA.

[kt3k]

@carragom Thank you for your contribution! I think this is a nice addtion to the API.

Can you run deno fmt command to the changed files?

[carragom]

Hi, thanks for the review, I formatted the files. But the reason the tests are failing is because the new test requires read access to be able to open the file with the encoded data. Not sure where to change that.

[kt3k]

@carragom Thanks! LGTM

[kt3k]

Note: mdn doesn't seem documenting ignoreBOM option? ref: https://developer.mozilla.org/en-US/docs/Web/API/TextDecoder/TextDecoder . But it's documented in whatwg spec https://encoding.spec.whatwg.org/#interface-textdecoder , and deno actually implements it.