Support "CONTAIN" filter condition

[jjoyce0510]

Describe the bug A clear and concise description of what the bug is.

Currently, the "CONTAIN" filter condition is not supported in Search, because the getQueryBuilderFromCriterion in SearchUtils class explicitly does not support it.

    final Condition condition = criterion.getCondition();
    if (condition == Condition.EQUAL) {
      if (criterion.getValue().startsWith("urn:li:")) {
        return QueryBuilders.termsQuery(criterion.getField(), criterion.getValue().trim());
      }
      return QueryBuilders.termsQuery(criterion.getField(), criterion.getValue().trim().split("\\s*,\\s*"));
    } else if (condition == Condition.GREATER_THAN) {
      return QueryBuilders.rangeQuery(criterion.getField()).gt(criterion.getValue().trim());
    } else if (condition == Condition.GREATER_THAN_OR_EQUAL_TO) {
      return QueryBuilders.rangeQuery(criterion.getField()).gte(criterion.getValue().trim());
    } else if (condition == Condition.LESS_THAN) {
      return QueryBuilders.rangeQuery(criterion.getField()).lt(criterion.getValue().trim());
    } else if (condition == Condition.LESS_THAN_OR_EQUAL_TO) {
      return QueryBuilders.rangeQuery(criterion.getField()).lte(criterion.getValue().trim());
    }

    throw new UnsupportedOperationException("Unsupported condition: " + condition);
  }```

(even though it exists in the Filter Condition enum.


#### To Reproduce

Steps to reproduce the behavior:

1. Deploy DataHub
2. Issue a Search Query with a specific "filter" criteria that has the condition "CONTAIN". You'll see a server error returned. 

![image](https://user-images.githubusercontent.com/17549204/125294210-efdd4080-e2d8-11eb-8a0d-143f87c93453.png)


#### Expected behavior

Contains operator should work for substring of string fields. 

As reported by Lal Rishav at Saxo Bank!

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#### Desktop (please complete the following information):

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- Browser [e.g. chrome, safari]
- Version [e.g. 22]

#### Additional context

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