base-files: /etc/banner: Add IOWRT logo and adapt text after image naming change

base-files: /etc/banner: Add IOWRT logo

Instead of IOPSYS (company) add IOWRT (software) ASCII logo. Original source for this has been generated using

echo IOWRT | toilet -W -f mono12

The following changes have been done afterwards:

• serifs removed (logo is sans-serif)
• "opened" R as in the logo
• increased kerning to resemble the logo more closely
• make "IO" cyan (basic 16 color-cyan supported by all terminals)

base-files: /etc/banner: Adapt after image naming change

Use CONFIG_VERSION_DIST to write IOWRT version. This way, it will also be the right text for downstream forks of our customers, who use CONFIG_VERSION_CODE for their version number. Hardcode OpenWrt to print the OpenWrt version, because we modify CONFIG_VERSION_DIST to be IOWRT since feed/iopsys commit a37729d885f4 (iop: config: Set version config-settings, 2022-09-19).