chore: license headers

[trentm]

Refs: #45

---

Note that for this change I excluded .eslintrc.js from being formatted so that the diff from the .eslintrc.json was more obvious. It can be removed from the exclude patterns for a separate PR.

[trentm]

The reason I changed from .eslintrc.json to .eslintrc.js is that I need to customize the config in each of the package dirs. The problem with eslint usage in the package dirs (e.g. in packages/mockotlpserver) is that it (a) runs with cwd set to the package dir, and (b) tries to load the "./scripts/license-header.js" from that dir. That file load fails. To work around that, I override that single rule in the sub dirs.

On the way to this workaround I tried:

• eslint-plugin-header (being used by OTel JS), and
• eslint-plugin-headers.

I rule out using those because they are awkward and most importantly, possibly destructive:
The former is just buggy in the face of top comments that it doesn't recognize (e.g. line-style comments, // this is my comment) or shebang lnes.

The later blindly replaces the top-comment in the file. So if you have a new file like this in VSCode, which is likely setup to run eslint --fix automatically on save:

// Here is some comment I spent some time on.

function hereIsSomeCode() {
  // ...
}

function thatIHaveBeenWorkingOn() {
}

then on save your carefully written top comment is blown away. You might not notice for a long while. If this is a new file then you likely don't have a git history to fall back on.