WE1.5.7 active moderators - update base model date-ranges

Summary

Updated date macros; then changed all date-range syntax in variable assignments and queries utilizing new date maros.

Rationale

This MR implements @amastilovic's suggested changes for standardizing date-range handling in dbt models, utilizing the macros that will be implemented via !105 (merged).

Specific changes

For the base_moderator_actions.sql and all upstream and downstream models, I did the following:

• Changed variable assignments from inclusive start and end dates to exclusive time ranges that rely on standardized macros.
• Updated date-range WHERE clause filtering to utilize new w time-range window in place of {{ start_date }} and {{ end_date }} inclusive filtering
• Made stylistic improvements, such as alias renames for clarity and deletion of redundant filters.