Only Search when a mininum number of characters where entered

When users do searchs they usually expect to do a search using more than 3 or 4 characters. Currently as soon as a user type in a character the mui-datatable start searching in all records, this could take 1 to 5 seconds to allow the user to type in the next character, this wait time depends on the quantity of rows in the table.

## Expected Behavior
Once the user enter a minimum # of characters (e.g. 4), the search would start search across all records in the mui-datatable OR another option could be that the user could trigger the search using the "ENTER" key (I would prefer this last option)

## Current Behavior
As soon as the user type in a character, the MUI-datatable starts searching over all records which could take seconds depending on the # of rows. So for ~400 records, the user needs to wait ~2-4 seconds to enter the next character. Even when using customSearch function, it always goes across all records in the table for the 1st character and all the process again for the subsequent characters.

| Tech | Version |
|--------------|---------|
| Material-UI | 3.9.2 |
| MUI-datatables | 2.0.0-beta.58 |
| React | 16.8.4 |
| browser | Firefox-chrome |
| etc | |