Bring several memory and access safety queries in from internal repo.

[NateD-MSFT]

This change adds the following queries:

• ConditionallyUninitializedVariableAutomation.ql: Flags calls to initialization functions whose return status is not checked, potentially leaving a local variable uninitialized.
• UnprobedDereference.ql: Detects dereferences of user-provided pointers that haven't been probed first, which could cause access violations.
• UserModeMemoryOutsideTry.ql: Finds reads of user-mode memory that occur outside a try/catch block, where unexpected exceptions from changed memory protections could crash the kernel.
• UserModeMemoryReadMultipleTimes.ql: identifies double-fetch vulnerabilities where user-mode memory is read more than once without being copied to kernel memory first.
• UnguardedNullReturnDereference.ql: Reports dereferences of return values from calls that may return NULL (e.g. heap allocations) without a preceding null check.