Fix comment range parsing for file comments in notedb

For file comments the line number 0 is written to the NoteDb. However
when reading the note and parsing the comment, a value of 0 was treated
as an error.

Provide unit test for file comment, with line equals 0. This test is
failing without this change being applied.

Change-Id: I837375a22368fbdcab9fc995761530623b0b2989
2 files changed