Build 19013

For general Windows information on build 19013 visit the Windows blog.

• [WSL2] Improve memory performance of WSL utility VM. Memory that is no longer in use will be freed back to the host.
• [WSL2] Update kernel version to 4.19.79. (add CONFIG_HIGH_RES_TIMERS, CONFIG_TASK_XACCT, CONFIG_TASK_IO_ACCOUNTING, CONFIG_SCHED_HRTICK, and CONFIG_BRIDGE_VLAN_FILTERING).
• [WSL2] Fix input relay to handle cases where stdin is a pipe handle that is not closed [GH 4424]
• Make the check for \\wsl$ case-insensitive.

[wsl2]
pageReporting = <bool>    # Enable or disable the free memory page reporting feature (default true).
idleThreshold = <integer> # Set the idle threshold for memory compaction, 0 disables the feature (default 1).