chore: lint .js and .mjs files (in addition to the existing .ts file linting)

[trentm]

In #2567 support
was added to eslint.config.js for linting .js and .mjs files -- before it
only supported .ts files.
Originally this was added to support linting examples/... which includes many
.js files.

This change enables linting of .js and .mjs files in the rest of the repo.

Refs: #2891

[trentm]

^^ the first commit is just the package.json changes. Subsequent commits will include lint:fix changes (and if necessary manual changes to for npm run lint to pass).

[trentm]

After running lint:fix (where 99% of changes were style-only tweaks to .eslintrc.js files), the only lint failures are in instr-aws-lambda:

      /Users/trentm/tm/opentelemetry-js-contrib2/packages/instrumentation-aws-lambda/test/lambda-test/async.js
        18:35  error  'event' is defined but never used    no-unused-vars
        18:42  error  'context' is defined but never used  no-unused-vars
        22:33  error  'event' is defined but never used    no-unused-vars
        22:40  error  'context' is defined but never used  no-unused-vars
        26:39  error  'event' is defined but never used    no-unused-vars
        26:46  error  'context' is defined but never used  no-unused-vars
        30:35  error  'event' is defined but never used    no-unused-vars
        30:42  error  'context' is defined but never used  no-unused-vars
        34:50  error  'event' is defined but never used    no-unused-vars
        34:57  error  'context' is defined but never used  no-unused-vars

      /Users/trentm/tm/opentelemetry-js-contrib2/packages/instrumentation-aws-lambda/test/lambda-test/sync.js
        22:27  error  'event' is defined but never used     no-unused-vars
        22:34  error  'context' is defined but never used   no-unused-vars
        22:43  error  'callback' is defined but never used  no-unused-vars
        30:33  error  'event' is defined but never used     no-unused-vars
        30:40  error  'context' is defined but never used   no-unused-vars
        30:49  error  'callback' is defined but never used  no-unused-vars

      ✖ 27 problems (16 errors, 11 warnings)

All are with the no-unused-vars rule.

Note that our eslint rules for TypeScript test files turn this rule off:

opentelemetry-js-contrib/eslint.config.js

Line 77 in 74ddb1e

"@typescript-eslint/no-unused-vars": "off",

We could do the same for .js files (Option 1), or add a more nuanced config something like this, which supports adding a leading _ to a var name to have it skip the "no-unused-vars" rule (Option 2):

        "no-unused-vars": [
            "error",
            {
                "vars": "all",
                "args": "all",
                "caughtErrors": "all",
                "argsIgnorePattern": "^_",
                "caughtErrorsIgnorePattern": "^_",
                "varsIgnorePattern": "^_"
            }
        ]

Anyone have opinions?

Update: In commit 092f156 I've done "Option 1".

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.05%. Comparing base (74ddb1e) to head (092f156).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2940      +/-   ##
==========================================
- Coverage   89.07%   89.05%   -0.02%     
==========================================
  Files         188      188              
  Lines        9223     9223              
  Branches     1900     1900              
==========================================
- Hits         8215     8214       -1     
- Misses       1008     1009       +1     

see 1 file with indirect coverage changes

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