Fix Markdown special characters not being escaped in web help

[t1m0thyj]

Fixes #620 and #323

• Fixed inconsistent behavior in DefaultHelpGenerator where Markdown special characters weren't always escaped in descriptions
• Fixed URL autolinking which stopped working in web help, by passing linkify option to markdown-it
• Fixed command descriptions not being detected if they begin with non-alphanumeric character (e.g., in the sample plugin)
• Fixed subgroups not being displayed under their own heading (e.g., in the @broadcom/caview-for-zowe-cli plugin)
• Updated Jenkinsfile to use npm@7 so that package-lock will stay at lockfile version 2 rather than getting reverted to version 1

[codecov]

Codecov Report

Merging #621 (32e87e0) into master (03a3772) will increase coverage by 0.25%.
The diff coverage is 97.82%.

@@            Coverage Diff             @@
##           master     #621      +/-   ##
==========================================
+ Coverage   82.13%   82.39%   +0.25%     
==========================================
  Files         162      163       +1     
  Lines        7768     7854      +86     
  Branches     1342     1367      +25     
==========================================
+ Hits         6380     6471      +91     
+ Misses       1384     1379       -5     
  Partials        4        4              

Impacted Files	Coverage Δ
packages/utilities/src/ImperativeConfig.ts	85.96% <ø> (ø)
packages/logger/src/Logger.ts	83.67% <88.88%> (-0.47%)	⬇️
packages/rest/src/client/AbstractRestClient.ts	81.10% <91.66%> (+1.36%)	⬆️
packages/cmd/src/CommandPreparer.ts	96.82% <100.00%> (ø)
packages/cmd/src/help/DefaultHelpGenerator.ts	97.38% <100.00%> (+0.04%)	⬆️
packages/cmd/src/help/WebHelpGenerator.ts	95.74% <100.00%> (+0.18%)	⬆️
packages/cmd/src/help/WebHelpManager.ts	93.75% <100.00%> (ø)
packages/cmd/src/response/CommandResponse.ts	97.04% <100.00%> (+1.50%)	⬆️
...erative/src/plugins/cmd/install/install.handler.ts	93.75% <100.00%> (ø)
...mperative/src/plugins/cmd/update/update.handler.ts	90.62% <100.00%> (ø)
... and 12 more

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[zFernand0]

Code changes look cool! 😋
I haven't approved it yet 😋
Will approve after generating the web help : )

[zFernand0]

thanks for fixing

[gejohnston]

Looks good.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities
0 Security Hotspots
1 Code Smell

92.9% Coverage
0.0% Duplication