Tweak missing property messages to improve clarity

[DrewML]

Description

Hey! Still learning I/O ins and outs, and went to copy some config in manifest.yml to create a second function for my application.

Unfortunately I missed some fields, specifically the runtime field. The following error message was flushed when running aio app deploy:

Error: Invalid or missing runtime in the manifest for this action: store-locator-extension-0.0.1/graphql

When I read this message, I was thinking of runtime more as an Adobe concept, and it didn't immediately occur to me that runtime was a property name.

Tweaked two error messages to (hopefully) add some clarity.

Related Issue

Motivation and Context

Easier onboarding for new folks

How Has This Been Tested?

Functionality is already covered by unit tests, just updated the error string we're asserting on

Screenshots (if appropriate):

Types of changes

• 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 #107 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #107   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          57     57           
  Lines        1737   1737           
  Branches      302    302           
=====================================
  Hits         1737   1737

Impacted Files	Coverage Δ
src/runtime-helpers.js	100% <100%> (ø)	⬆️

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