Introduce @gitlab/eslint-config 3.0.0

What

Introduces @gitlab/eslint-config 3.0.0. .eslintrc is updated as well.

extend

Required to introduce @gitlab/eslint-config

rules

All rules which both are defined in @gitlab/eslint-config and cause errors without code changes are disabled in this MR. This is the easiest way to introduce meaningful rules to the project.

Why is this change being made?

JavaScript files in this project have not been tested as eslint configuration is not enough. Rules are adapted with low-cost by introducing @gitlab/eslint-config 3.0.0.

The following is a list of suppressed rules with the numbers of errors:

 642 no-var
 212 vars-on-top
 108 prefer-template
  94 object-shorthand
  48 no-undef
  39 no-use-before-define
  37 filenames/match-regex
  32 no-plusplus
  24 no-restricted-globals
  24 eqeqeq
  18 block-scoped-var
  12 no-redeclare
  11 prefer-destructuring
  11 no-unused-vars
  11 no-multi-assign
  10 no-param-reassign
   8 strict
   7 no-unused-expressions
   4 no-shadow
   4 no-restricted-syntax
   3 no-else-return
   2 spaced-comment
   2 no-underscore-dangle
   2 no-new-wrappers
   2 no-implicit-coercion
   2 lines-around-directive
   2 import/no-extraneous-dependencies
   2 babel/camelcase
   2 array-callback-return
   1 radix
   1 promise/always-return
   1 prefer-const
   1 one-var
   1 no-useless-concat
   1 no-return-assign
   1 no-new
   1 no-loop-func
   1 no-inner-declarations
   1 no-bitwise
   1 import/prefer-default-export
   1 import/no-unresolved
   1 import/extensions
   1 dot-notation
   1 consistent-return

Does this MR meet the acceptance criteria?

Assign to DRI

• Did you assign this change to the correct DRI of the page or information you are changing?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what

Ref.

• !41790 (merged)