fix(mssql): use picodb ORM for subtask timer query, rather than hardcoded SQL
fix(mssql): use picodb ORM for subtask timer query, rather than hardcoded SQL

the hardcoded SQL was failing on MSSQL because 'end' is a reserved keyword
and thus must be escaped
escape identifiers within subtask timer subquery conditions
serialize and interpolate values into text after generation

renothing/kanboard,renothing/kanboard,kanboard/kanboard,renothing/kanboard,kanboard/kanboard,kanboard/kanboard