ci(linting): add remaining linting and formatting checks

[CameronMcClymont]

Introduce remaining file formatting checks to run-tests.sh and to the GitHub CI:

• .editorconfig for consistent character formatting across the repo
• yamllint for YAML linting
• jsonlint for JSON linting
• shfmt for shell script formatting
• markdownlint for markdown linting
• prettier for various other formatting such as .js files

Closes #230

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 27.65%. Comparing base (f32aafd) to head (acb707f).
Report is 5 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #231   +/-   ##
=======================================
  Coverage   27.65%   27.65%           
=======================================
  Files           5        5           
  Lines         141      141           
=======================================
  Hits           39       39           
  Misses        102      102           

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[tiborsimko]

Having introduces everything in one single commit, instead of adding each linter/formatter separately, may be acceptable -- but then we would have to alter the commit log headline message in order to produce nicer release news item for users. (Because people would not understand "add remaining linting and formatting checks" -- which remaning?) One possibility would be to write something like "add JSON, Markdown, Prettier, shmft, YAML formatting and linting" if it is not too long.

Alternatively, you can just split the commit into several dedicated atomic ones, starting with shfmt, as yet another git rebasing exercise...

See an example of such automatically generated release notes: reanahub/reana-workflow-controller#578

[tiborsimko]

Cosmetics: Let's use a blank line between these two rules?

[CameronMcClymont]

Ah yes, understood. I'll see if it's difficult to split the commits.

[CameronMcClymont]

It seems doable splitting the commits, I might not get round to all of them today

[tiborsimko]

I wonder whether Release Please will reintruduce empty lines when compiling next release notes. If so, then it would be better if we add another markdownlint disable statement...

[CameronMcClymont]

Ah yes will do 👍

[tiborsimko]

Thanks, slightly amended the commit log headlines for nicer release notes.