Use shellcheck for linting code

[Potherca]

You might want to strat using Shellcheck to lint shell code for possible issues.

The current run gives us:

[Line 4:](javascript:setPosition(4, 1))
[[ -z "$INGEST_KEY" ]] && echo "INGEST_KEY not set" && exit 1
^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
 
[Line 25:](javascript:setPosition(25, 14))
  data=$(cat go.list | base64)
             ^-- [SC2002](https://github.com/koalaman/shellcheck/wiki/SC2002) (style): Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.
 
[Line 39:](javascript:setPosition(39, 14))
  data=$(cat pom.xml | base64)
             ^-- [SC2002](https://github.com/koalaman/shellcheck/wiki/SC2002) (style): Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.
 
[Line 52:](javascript:setPosition(52, 17))
  content=$(cat package.json | base64)
                ^-- [SC2002](https://github.com/koalaman/shellcheck/wiki/SC2002) (style): Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.
 
[Line 54:](javascript:setPosition(54, 6))
  if [[ -e "package-lock.json" ]]; then
     ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
 
[Line 55:](javascript:setPosition(55, 19))
    content=$(cat package-lock.json | base64)
                  ^-- [SC2002](https://github.com/koalaman/shellcheck/wiki/SC2002) (style): Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.
 
[Line 57:](javascript:setPosition(57, 8))
  elif [[ -e "yarn.lock" ]]; then
       ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
 
[Line 58:](javascript:setPosition(58, 19))
    content=$(cat yarn.lock | base64)
                  ^-- [SC2002](https://github.com/koalaman/shellcheck/wiki/SC2002) (style): Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.
 
[Line 91:](javascript:setPosition(91, 9))
  while [[ $# -gt 0 ]]; do
        ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
 
[Line 106:](javascript:setPosition(106, 12))
        if [[ ! -z "$OWN_MODULES" ]]; then
           ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
              ^-- [SC2236](https://github.com/koalaman/shellcheck/wiki/SC2236) (style): Use -n instead of ! -z.
 
[Line 113:](javascript:setPosition(113, 12))
        if [[ ! -z "$OWN_SCOPES" ]]; then
           ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
              ^-- [SC2236](https://github.com/koalaman/shellcheck/wiki/SC2236) (style): Use -n instead of ! -z.
 
[Line 131:](javascript:setPosition(131, 3))
  [[ -z "$ENTITY" ]] && print_help && exit 1
  ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
 
[Line 132:](javascript:setPosition(132, 3))
  [[ -z "$REPO" ]] && print_help && exit 1
  ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
 
[Line 134:](javascript:setPosition(134, 6))
  if [[ "$TYPE" = "go.list" ]] && [[ -e "go.list" ]]; then
     ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
                                  ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
 
[Line 138:](javascript:setPosition(138, 6))
  if [[ "$TYPE" = "pom.xml" ]] && [[ -e "pom.xml" ]]; then
     ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
                                  ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
 
[Line 142:](javascript:setPosition(142, 6))
  if [[ "$TYPE" = "package.json" ]] && [[ -e "package.json" ]]; then
     ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.
                                       ^-- [SC3010](https://github.com/koalaman/shellcheck/wiki/SC3010) (warning): In POSIX sh, [[ ]] is undefined.

When time allows, I could open an MR with fixes and a GitHub Workflow to check any future changes against Shellcheck?