chore: end of support for nodejs12x runtime

[dreamorosi]

Description of your changes

This PR removes support for Node.js 12. This includes the following changes:

• Update config files fro GitHub CodeSpaces & GitPod
• Remove runtime from the test matrixes in CI/CD workflows
• Remove runtime from compatible layers
• Change engine value in package.json to >=14
• Remove related commands from utilities' package.json files

Find more info on the deprecation in the linked issue (#1061).

How to verify this change

Review diff, check results of unit tests, and integration tests (see comment below).

Related issues, RFCs

Issue number: #1061

PR status

Is this ready for review?: YES
Is it a breaking change?: NO

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding changes to the examples
• My changes generate no new warnings
• The code coverage hasn't decreased
• I have added tests that prove my change is effective and works
• New and existing unit tests pass locally and in Github Actions
• Any dependent changes have been merged and published
• The PR title follows the conventional commit semantics

Breaking change checklist

• I have documented the migration process
• I have added, implemented necessary warnings (if it can live side by side)

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[github-actions]

📊 Package size report   -0.58%↓

File	Before	After
aws-lambda-powertools-commons-1.5.0.tgz	10.3 kB	-0.53%↓10.2 kB
aws-lambda-powertools-logger-1.5.0.tgz	25.1 kB	-0.78%↓24.9 kB
aws-lambda-powertools-metrics-1.5.0.tgz	17.9 kB	-0.39%↓17.9 kB
aws-lambda-powertools-tracer-1.5.0.tgz	22.5 kB	-0.72%↓22.4 kB
commons-bundle.zip	10.7 kB	0.2%↑10.8 kB
logger-bundle.zip	25.6 kB	-0.68%↓25.4 kB
metrics-bundle.zip	18.4 kB	-0.45%↓18.3 kB
tracer-bundle.zip	23.1 kB	-0.75%↓22.9 kB
Total (Includes all files)	153.6 kB	-0.58%↓152.7 kB
Tarball size	152.5 kB	-0.55%↓151.7 kB

_{🤖 This report was automatically generated by pkg-size-action}
(options hash: bdb2e35d176eda92228e3e4fcc9a1de5)

[dreamorosi]

Integration tests are passing:
https://github.com/awslabs/aws-lambda-powertools-typescript/actions/runs/3705085226