Add ability to use WITH SECURITY_ENFORCED to QueryFactory

[SWhalen-gh]

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I wanted to suggest that fflib_QueryFactory should provide the option of implementing security with Salesforce's recent "WITH SECURITY_ENFORCED" ( WITH SECURITY ENFORCED ).

This was mentioned briefly towards the end of the discussion in #199 but I didn't see any further mention of it.

For backwards compatibility, the library could leave the old flags and old implementation, but add new flag that would add "WITH SECURITY_ENFORCED" to the query string.