Make manifest_check errors colorful.

Insert ANSI escape codes in the error text. Colors are red, blue, green
and some text is in bold --- these are all bright enough on either dark
or light background.

Also, add a link to the online documentation.

Bug: 132357300
Test: manually mangle one of Android.bp files to get a manifest_check
  error and observe that it is colorful.
Change-Id: I2af2aa0415d0eb0eabc88dc5504198e11bfb91b6