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: OS#6642

pySim/ts_102_222.py

@@ -25,6 +25,16 @@ from osmocom.utils import b2h, auto_uint8, auto_uint16, is_hexstr
 
 from pySim.ts_102_221 import *
 
+def expand_pattern(pattern: bytes, repeat: bool, size: int) -> bytes:
+    """Expand the fill/repeat pattern as per TS 102 222 Section 6.3.2.2.2 Tags C1/C2."""
+    if not repeat:
+        pad_len = size - len(pattern)
+        return pattern + pattern[-1:] * pad_len
+    else:
+        count = size // len(pattern)
+        part_len = size - count * len(pattern)
+        return pattern * count + pattern[:part_len]
+
 @with_default_category('TS 102 222 Administrative Commands')
 class Ts102222Commands(CommandSet):
     """Administrative commands for telecommunication applications."""