[CI] Enable Shell checks

[shahmishal]

Run apt-get -qq update && apt-get -qq -y install shellcheck
  apt-get -qq update && apt-get -qq -y install shellcheck
  git ls-files -z '*.sh' | xargs -0 --no-run-if-empty shellcheck
  shell: sh -e {0}
debconf: delaying package configuration, since apt-utils is not installed
Selecting previously unselected package shellcheck.
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Preparing to unpack .../shellcheck_0.9.0-1_amd64.deb ...
Unpacking shellcheck (0.9.0-1) ...
Setting up shellcheck (0.9.0-1) ...

In assets/test/sleep.sh line 1:
sleep $1
^-- SC2148 (error): Tips depend on target shell and yours is unknown. Add a shebang or a 'shell' directive.
      ^-- SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 
sleep "$1"


In assets/test/sleep.sh line 2:
exit $2
     ^-- SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 
exit "$2"


In docker/test-ci.sh line 1:
#!/usr/bin/env node
^-- SC1008 (error): This shebang was unrecognized. ShellCheck only supports sh/bash/dash/ksh. Add a 'shell' directive to specify.


In docker/test-ci.sh line 3:
const { execSync } = require('child_process');
      ^-- SC1083 (warning): This { is literal. Check expression (missing ;/\n?) or quote it.
                 ^-- SC1083 (warning): This } is literal. Check expression (missing ;/\n?) or quote it.
                            ^-- SC1036 (error): '(' is invalid here. Did you forget to escape it?
                            ^-- SC1088 (error): Parsing stopped here. Invalid use of parentheses?


In docker/test.sh line 1:
set -ex
^-- SC2148 (error): Tips depend on target shell and yours is unknown. Add a shebang or a 'shell' directive.


In docker/test.sh line 21:
(xvfb-run -a npm run coverage; echo $? > exitcode) | grep -Ev "Failed to connect to the bus|GPU stall due to ReadPixels" && rm -rf "${current_directory}/coverage" && (cp -R ./coverage $current_directory || true)
                                                                                                                                                                                        ^----------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 
(xvfb-run -a npm run coverage; echo $? > exitcode) | grep -Ev "Failed to connect to the bus|GPU stall due to ReadPixels" && rm -rf "${current_directory}/coverage" && (cp -R ./coverage "$current_directory" || true)


In docker/test.sh line 22:
exit $(<exitcode)
     ^----------^ SC2046 (warning): Quote this to prevent word splitting.


In scripts/soundness.sh line 92:
  expected_lines=$(cat "$tmp" | wc -l)
                       ^----^ SC2002 (style): Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.


In scripts/soundness.sh line 93:
  expected_sha=$(cat "$tmp" | shasum)
                     ^----^ SC2002 (style): Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.


In scripts/soundness.sh line 115:
    } | while read line; do
              ^--^ SC2162 (info): read without -r will mangle backslashes.


In scripts/soundness.sh line 116:
      if [[ "$(cat "$line" | replace_acceptable_years | head -n $expected_lines | shasum)" != "$expected_sha" ]]; then
                   ^-----^ SC2002 (style): Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.
                                                                ^-------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 
      if [[ "$(cat "$line" | replace_acceptable_years | head -n "$expected_lines" | shasum)" != "$expected_sha" ]]; then


In scripts/soundness.sh line 117:
        printf "\033[0;31mmissing headers in file '$line'!\033[0m\n"
               ^-- SC2059 (info): Don't use variables in the printf format string. Use printf '..%s..' "$foo".


In scripts/soundness.sh line 118:
        diff -u <(cat "$line" | replace_acceptable_years | head -n $expected_lines) "$tmp"
                      ^-----^ SC2002 (style): Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.
                                                                   ^-------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 
        diff -u <(cat "$line" | replace_acceptable_years | head -n "$expected_lines") "$tmp"


In scripts/tag_release.sh line 20:
    exit -1
         ^-- SC2242 (error): Can only exit with status 0-255. Other data should be written to stdout/stderr.

For more information:
  https://www.shellcheck.net/wiki/SC1008 -- This shebang was unrecognized. Sh...
  https://www.shellcheck.net/wiki/SC2148 -- Tips depend on target shell and y...
  https://www.shellcheck.net/wiki/SC2242 -- Can only exit with status 0-255. ...
Error: Process completed with exit code 123.

[plemarquand]

Verify in 51ec25c