tests for new Identify distro func

Signed-off-by: Alfredo Deza <adeza@anchore.com>

imgbom/distro/test-fixtures/os/ubuntu-20.04/etc/os-release

@@ -0,0 +1,12 @@
+NAME="Ubuntu"
+VERSION="20.04 LTS (Focal Fossa)"
+ID=ubuntu
+ID_LIKE=debian
+PRETTY_NAME="Ubuntu 20.04 LTS"
+VERSION_ID="20.04"
+HOME_URL="https://www.ubuntu.com/"
+SUPPORT_URL="https://help.ubuntu.com/"
+BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
+PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
+VERSION_CODENAME=focal
+UBUNTU_CODENAME=focal

imgbom/distro/test-fixtures/os/unmatchable/etc/os-release

@@ -0,0 +1,17 @@
+NAME="Scientific Linux"
+VERSION="16 (Core)"
+ID="scientific"
+ID_LIKE="rhel fedora"
+VERSION_ID="8"
+PLATFORM_ID="platform:el8"
+PRETTY_NAME="CentOS Linux 8 (Core)"
+ANSI_COLOR="0;31"
+CPE_NAME="cpe:/o:centos:centos:8"
+HOME_URL="https://www.centos.org/"
+BUG_REPORT_URL="https://bugs.centos.org/"
+
+CENTOS_MANTISBT_PROJECT="CentOS-8"
+CENTOS_MANTISBT_PROJECT_VERSION="8"
+REDHAT_SUPPORT_PRODUCT="centos"
+REDHAT_SUPPORT_PRODUCT_VERSION="8"
+