chore(lint): add eslint header and baseline rules

[overbalance]

What problem is this solving?

Adds ESLint rules for browser compatibility checking (baseline) and license header enforcement to ensure code quality and compliance.

Short description of changes

• Add eslint with eslint-plugin-baseline-js for browser compatibility linting
• Add license header enforcement using eslint-plugin-yet-another-license-header, thanks @trentm!
• Configure to lint only packages/*/src/**/*.{js,ts,mjs} files

Testing

• npm run lint passes

[trentm]

Is this effectively duplicating biome linting? I understand they aren't identical.

[overbalance]

No, it's not. This is only running the baseline plugin and the header plugin which are not available in the biome plugin format. Both features are essential so while running biome and eslint is not ideal, it's still a major speed up from running eslint recommended rules on its own.

[trentm]

This won't allow for extra copyright assignments. See, for example, https://github.com/open-telemetry/opentelemetry-js-contrib/blob/main/packages/instrumentation-oracledb/src/instrumentation.ts
Currently nothing in this repo requires a separate copyright assignment, so this works for now.

Could perhaps do this:

Suggested change

	/^\/\*\n \* Copyright The OpenTelemetry Authors\n \* SPDX-License-Identifier: Apache-2\.0\n \*\/$/;
	/^\/\*\n \* Copyright The OpenTelemetry Authors(?:, [^\n]+)*\n \* SPDX-License-Identifier: Apache-2\.0\n \*\/$/;

[overbalance]

That was an oversight. I just fixed so it matches contrib to allow for comma-delimited vendors on the same line as OTel, as well as on the next line, with an optional line break after