MDL-46536: OAuth signature fails with inconsistent new lines

When the LTI intro contains a single \n or
\r newline character then the OAuth signature
fails.  All newlines should be \r\n
Merge branch 'MDL-46536_oauthSig' of https://github.com/moodlerooms/moodle
MDL-46302 correct atto img float right

Correct the atto image "float right" margin CSS