Add viewability to e-planning bid adapter

[fndigrazia]

Type of change

• Feature

Description of change

This PR adds viewability tracking to our e-planning bid adapter, and changes one of our request parameters. It also fixes #4132

Other information

We added an observer to be able to track adunits whose divs weren't yet rendered when buildRequests is first called. Unfortunately we ran into some problems while testing this feature, due to its asynchronous nature, the test code was finishing before the observer callback was called. Any ideas on how we can test this? Thanks.

[bretg]

Unit tests are broken with this change. I re-ran them many times. Failure is

IE 11.0.0 (Windows 10.0.0) ERROR
  {
    "message": "Object doesn't support property or method 'forEach'\nat webpack:///modules/eplanningBidAdapter.js:218:6 <- test/test_index.js:139444:7\n\nTypeError: Object doesn't support property or method 'forEach'\n   at Anonymous function (webpack:///modules/eplanningBidAdapter.js:218:6 <- test/test_index.js:139444:7)\n   at Anonymous function (webpack:///modules/eplanningBidAdapter.js:217:4 <- test/test_index.js:139443:5)",
    "str": "Object doesn't support property or method 'forEach'\nat webpack:///modules/eplanningBidAdapter.js:218:6 <- test/test_index.js:139444:7\n\nTypeError: Object doesn't support property or method 'forEach'\n   at Anonymous function (webpack:///modules/eplanningBidAdapter.js:218:6 <- test/test_index.js:139444:7)\n   at Anonymous function (webpack:///modules/eplanningBidAdapter.js:217:4 <- test/test_index.js:139443:5)"
  }

[fndigrazia]

Fixed the observed error but unrelated tests failed

[Nistenf]

Checks are now green

[sebaperez]

Hi @bretg @mike-chowla any update regarding this? Could it be merged? Thanks!

[mike-chowla]

LGTM