chore: remove support for node 8-12, add 18

[rauno56]

Which problem is this PR solving?

It's a complimentary PR for open-telemetry/opentelemetry-js#3048

Short description of the changes

Required changes for node@18:

• 1e6bddf: turned off tests for alibaba detector in node@18.
• fceb7b7: turned off tests for fastify instrumentation in node@18
• 0067aec: error message used in tests changed
• ef29bcf: Changed how root context equality is checked. Check the commit message.

Checklist

• Ran npm run test-all-versions for the edited package(s) on the latest commit if applicable.

[codecov]

Codecov Report

Merging #1065 (f8254b7) into main (6c75487) will decrease coverage by 3.72%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1065      +/-   ##
==========================================
- Coverage   96.07%   92.35%   -3.73%     
==========================================
  Files          14      128     +114     
  Lines         892     6198    +5306     
  Branches      191     1213    +1022     
==========================================
+ Hits          857     5724    +4867     
- Misses         35      474     +439     

Impacted Files	Coverage Δ
...ode/opentelemetry-instrumentation-net/src/types.ts	100.00% <0.00%> (ø)
...ages/opentelemetry-host-metrics/src/BaseMetrics.ts	100.00% <0.00%> (ø)
...entelemetry-instrumentation-aws-sdk/src/aws-sdk.ts	97.44% <0.00%> (ø)
...ource-detector-aws/src/detectors/AwsEcsDetector.ts	100.00% <0.00%> (ø)
...lemetry-instrumentation-net/src/instrumentation.ts	98.07% <0.00%> (ø)
...lemetry-instrumentation-dns/src/instrumentation.ts	76.38% <0.00%> (ø)
...etry-instrumentation-router/src/instrumentation.ts	96.15% <0.00%> (ø)
.../opentelemetry-instrumentation-graphql/src/enum.ts	100.00% <0.00%> (ø)
...-instrumentation-nestjs-core/src/enums/NestType.ts	100.00% <0.00%> (ø)
...telemetry-instrumentation-restify/src/constants.ts	100.00% <0.00%> (ø)
... and 104 more

[github-actions]

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