Identify more platforms and externalize environment checking

[mmorel-35]

Hi @radu-matei , this PR includes the npm audit fix.
Please merge it first so the other PR won't fail.

1. This PR externalizes the environment checking in a dedicated file.

The checking consist in :

• ensure that the required environment variables are available
• ensure that docker is available
• ensure that the request version of Kind supports the current platform
• print a warning if setup-kind doesn't support the current platform
• print a warning if the image doesn't include a sha256

2. Kubectl is now installed with the right version when kubernetes version can be identified throught the provided image or the kind config file

3. A metallb load-balancer can be installed with loadBalancer : true

4. A local registry can be installed with localRegistry : true

NB : latest can be a valid value for the kind version input parameter

closes #9
closes #16
closes #81

[codecov-commenter]

Codecov Report

Merging #71 (5c5bbdf) into master (eb0371b) will decrease coverage by 14.87%.
The diff coverage is 34.56%.

@@             Coverage Diff             @@
##           master      #71       +/-   ##
===========================================
- Coverage   62.81%   47.94%   -14.88%     
===========================================
  Files           6       10        +4     
  Lines         199      340      +141     
  Branches       34       53       +19     
===========================================
+ Hits          125      163       +38     
- Misses         70      171      +101     
- Partials        4        6        +2     

Impacted Files	Coverage Δ
src/requirements.ts	14.14% <14.14%> (ø)
src/go.ts	29.41% <16.66%> (-3.93%)	⬇️
src/kind/post.ts	63.33% <40.00%> (-3.91%)	⬇️
src/local-registry.ts	42.00% <42.00%> (ø)
src/kubectl.ts	50.00% <50.00%> (ø)
src/yaml/helper.ts	50.00% <50.00%> (ø)
src/kind/main.ts	78.37% <57.14%> (+9.62%)	⬆️
src/docker.ts	66.66% <66.66%> (ø)
src/constants.ts	96.96% <90.90%> (-3.04%)	⬇️
src/kind/core.ts	75.00% <100.00%> (+15.00%)	⬆️
... and 1 more

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[mmorel-35]

Please @radu-matei , when do you think you'll find the time to review this ?
Thank you!