Add support in dplyr api for has, contains, matches regex etc. string operators

[hongooi73]

No description provided.

[alexkyllo]

Arbitrary KQL operators can be used by surrounding with %
E.g.
filter(Url %matches regex% "https://docs.microsoft.com/([^/]*)/cli/azure/")
gets translated correctly as
| where ['Url'] matches regex 'https://docs.microsoft.com/([^/]*)/cli/azure/'

The one that doesn't work right is %in% because it's overloaded with %in% ([Table or Query]). I will work on a patch to fix that. Workaround in the meantime is to use %in~% which is the case-insensitive version.