Implement date range support for Nextgen Query language

[thavlice]

Currently, to express date range we need to use two terms and typical ranges are kind of bothersome for users to write.

For example the to get all entities for the month August, we need to do
created:>=2025-08 created:<2025-09.

Nicer solution would be grammar similar to:
created:2025-08..2025-09 for the specified date range

and maybe also abstraction for duration of period (week, month, year)
created:2025-08.. or similar.

DoD:

• Implement date range support for query language