fix(fastly) provide service version and other contextual information

[bosschaert]

Description

Provide additional contextual details in the context parameter passed to the main function for services running in Fastly Compute@Edge.

The following fields (which were previously null) are now set:

• context.func.name: the service ID
• context.func.fqn: A globally unique function identifier which includes the service ID and version
• context.func.version: the fastly service version - typically a whole number that automatically increases with every deploy
• context.invocation.requestId: An ID uniquely associated with the current request
• context.invocation.transactionId: The x-transaction-id header from the request or otherwise a unique ID associated with the current request.
• context.runtime.region: The region as 3-letter point-of-present code where the service is executed, see here for codes: https://developer.fastly.com/learning/concepts/pop

Usage example:

module.exports.main = async function main(req, context) {
  return new Response(`Executed in version: ${context?.func?.version}
      Region: ${context?.runtime?.region}
      Func Name: ${context?.func?.name}
      Func FQN: ${context?.func?.fqn}
      TxID: ${context?.invocation?.transactionId}
      ReqID: ${context?.invocation?.requestId}`);
}

Related Issue

Fixes: #598

Motivation and Context

It allows to determine with certainty what version of the function is being invoked (sometimes an update can take a while) and provides additional information which can be useful for tracing and debugging.

How Has This Been Tested?

A new unit test has been added: fastly-adapter.test.js.

Types of changes

As the fields for this information were there but not filled in I consider this a bug fix.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov]

Codecov Report

Merging #608 (d9b5f78) into main (63991db) will decrease coverage by 1.26%.
Report is 5 commits behind head on main.
The diff coverage is 15.78%.

@@            Coverage Diff             @@
##             main     #608      +/-   ##
==========================================
- Coverage   73.83%   72.57%   -1.26%     
==========================================
  Files          24       25       +1     
  Lines        5751     5878     +127     
  Branches        1        1              
==========================================
+ Hits         4246     4266      +20     
- Misses       1505     1612     +107     

Files	Coverage Δ
src/bundler/EdgeBundler.js	92.12% <100.00%> (+0.06%)	⬆️
src/deploy/ComputeAtEdgeDeployer.js	97.95% <100.00%> (ø)
src/template/fastly-adapter.js	15.07% <11.11%> (ø)

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[github-actions]

This PR will trigger no release when merged.