Allow samples cache directory to be created if non-existent

[michael-valdron]

Please specify the area for this PR

build-tools

What does does this PR do / why we need it:

Changes mkdir $samplesDir/$sample to mkdir -p $samplesDir/$sample to allow target cache directories which do not exist yet.

Which issue(s) this PR fixes:

Fixes #?

fixes devfile/api#1553

PR acceptance criteria:

• Test Coverage
  • Are your changes sufficiently tested, and are any applicable test cases added or updated to cover your changes?

Documentation (WIP)

• Does the REST API doc need to be updated with your changes?
• Does the registry library doc need to be updated with your changes?

How to test changes / Special notes to the reviewer:

Run bash build-tools/cache_samples.sh extraDevfileEntries.yaml <non_existent_caching_path>

[michael-valdron]

• Test Coverage
  • Are your changes sufficiently tested, and are any applicable test cases added or updated to cover your changes?

Documentation (WIP)

• Does the REST API doc need to be updated with your changes?
• Does the registry library doc need to be updated with your changes?

N/A

[Jdubrick]

After these changes I was able to run it on MacOS

[Jdubrick]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Jdubrick, michael-valdron

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