Add support for `ContactsContract.RawContacts.DIRTY`

[vestrel00]

Problem

As discussed in #353 with @lati111, this library currently does not support reading and writing the value of RawContact's ContactsContract.SyncColumns.DIRTY, which is a critical components to sync adapter operations.

Solution

Add dirty field to RawContactEntity and support CRUD operations for it.

• Check behavior in Insert
• Check behavior in ProfileInsert
• Check behavior in Update
• Check behavior in ProfileUpdate
• Check behavior in Insert
• Check behavior in Delete (e.g. delete by matching dirty using WHERE clause)
• Check behavior in ProfileDelete (e.g. delete by matching dirty using WHERE clause)
• Check behavior in Query
• Check behavior in BroadQuery
• Check behavior in PhoneLookupQuery
• Check behavior in RawContactsQuery
• Check behavior in MoveRawContactsAcrossAccounts
• Check behavior in ContactLink
• Check behavior in ContactUnlink
• Check behavior in Insert
• Update all in-code documentation
• Update docs, where necessary
• Update gh-pages branch