[5.6] Fix dateBasedWhere() with raw expressions in SQLite

[staudenmeir]

whereDate(), whereMonth() etc. don't work with raw expressions in SQLite:

DB::table('users')->whereDate('created_at', DB::raw('NOW()'))->toSql();
// expected: select * from "users" where strftime('%Y-%m-%d', "created_at") = NOW()
// actual:   select * from "users" where strftime('%Y-%m-%d', "created_at") = ?

This line causes the problem:

framework/src/Illuminate/Database/Query/Grammars/SQLiteGrammar.php

Line 141 in 4306de8

$value = str_pad($where['value'], 2, '0', STR_PAD_LEFT);

The code looks like it pads days/months from 1 to 01 when calling whereDay()/whereMonth().

But since the value is added to the bindings before this is called, it has no effect. In the next line $this->parameter() replaces it with the placeholder ?.

This PR adds raw expression tests for all databases and also missing whereDate() tests.