Changes

esim.saip: Fix computation of file content

When generating the file content (body), we need to proceed in the
following order:

1a) If FCP contains fillPattern/repeatPattern, compute file content from those

1b) If FCP doesn't contain fillPattern/repeatPattern but template
    exists, compute file content from template

2)  Apply any fillFileConten / fillFileOffset from the SAIP File on top
    of the above

Change-Id: I822bb5fbec11a3be35910a496af7168458fd949c
Closes: #6642