add one_color_no_palette.webp

this lossless file was produced with:
b6513fba Do not use a palette for one color images.

at 28 bytes it exercises a minimum size check failure in chrome and a one
color image related failure in safari/ios/macos.

https://chromium-review.googlesource.com/c/chromium/src/+/2876279

Bug: b/186640109,b/188702956
Change-Id: Ibb05749a4ff04228f70ae37501ee64fdf234e566