Logo (Builtin): add ObsidianOS

[neoapps-dev]

Add support for ObsidianOS logo.

More info about ObsidianOS:
An Arch-based distro with A/B Partition Layout. Website, GitHub Organization, Docs

Screenshot (on VM):

/etc/os-release:

NAME="ObsidianOS"
PRETTY_NAME="Obsidian GNU/Linux"
ID=obsidian
BUILD_ID=rolling
ANSI_COLOR=38;2;138;43;226
HOME_URL="https://github.com/obsidian-os"
DOCUMENTATION_URL="https://obsidian-os.github.io/docs"
SUPPORT_URL="https://github.com/orgs/Obsidian-OS/discussions"
BUG_REPORT_URL="https://github.com/obsidian-os/issue-tracker/issues"
PRIVACY_POLICY_URL="https://terms.archlinux.org/docs/privacy-policy/"
LOGO=obsidianos

Build tested only on Arch, should work on all of em tho

Hope to see it get merged :)