#1721 Replace codemirror-lang-r package with @codemirror/legacy-modes

[nmgokhale]

Fixes #1721

Jest tests are failing with @codemirror/legacy-modes package as well. To fix jest tests, host applications should add this config in package.json file -

"jest": {
    "transformIgnorePatterns": [
      "node_modules/@elyra/canvas/node_modules/(?!@codemirror/legacy-modes)"
    ]
  }

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[nmgokhale]

At path canvas_modules/common-canvas/node_modules/@codemirror/legacy-modes/mode, I do see r.cjs file. Hopefully host applications won't see any issue in CommonJS format.

[matthoward366]

Looks good