Build 18980

For general Windows information on build 18980 visit the Windows blog.

• Fix reading symlinks that deny FILE_READ_DATA. This includes all the symlinks Windows creates for backwards compatibility such as "C:\Document and Settings" and a bunch of symlinks in the user profile directory
• Make unexpected filesystem state non-fatal [GH 4334, 4305]
• [WSL2] Add support for arm64 if your CPU / firmware supports virtualization
• [WSL2] Allow unprivileged users to view kernel log
• [WSL2] Fix output relay when stdout / stderr sockets have been closed [GH 4375]
• [WSL2] Support battery and AC adapter passthrough
• [WSL2] Update Linux kernel to 4.19.67
• Add the ability to set default username in /etc/wsl.conf:

[user]
default=root