feat(examples): added sam example to workflows

[dreamorosi]

Description of your changes

In a recent PR (#674) we received a contribution that added SAM examples to the repo. This PR aims at incorporating these examples into the CI/CD workflows we have at the moment. This includes linting of the sources, as well as building (sam build), and extremely basic unit tests that ensure that the functions can be imported & called.

List of changes:

• Changed symlink from examples/sam/src/handlers to examples/sam/src, to conform to the structure needed by the linting commands (updated README & template.yml, no effect on the actual sample).
• Added config files needed for the sample to be part of the workflows (tsconfig, jest.config, package-lock, etc.).
• Added scripts stanza to the package.json to support various commands.
• Added the sample to lerna's configs.
• Modified workflows to include additional step that installs dependencies in the sample folder.
• Added basic jest tests (full coverage of these functions is out of scope at the moment).
• Fixed linting issues.
• Minor housekeeping in another file belonging to the examples/cdk folder that I came across while copying parts of the code.

How to verify this change

Check the execution result of the GitHub actions included in this PR.

Related issues, RFCs

#674

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
• The PR title follows the conventional commit semantics

Breaking change checklist

N/A

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