Playlist: recreate playlist content on restore

When restoring a playlist, create its content as external media, so that
it is not restored empty.
4 jobs for restore in 22 minutes and 51 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Test
failed #302054
amd64 debian
asan-ubsan

00:22:19

failed #302051
amd64 debian
linux

00:18:58

failed #302052
win32
win32

00:22:31

failed #302053
win64
win64

00:22:51

 
Name Stage Failure
failed
win64 Test

[----------] Global test environment tear-down
[==========] 173 tests from 5 test cases ran. (730400 ms total)
[ PASSED ] 172 tests.
[ FAILED ] 1 test, listed below:
[ FAILED ] MiscTests.ExportRestorePlaylist

1 FAILED TEST
ERROR: Job failed: exit code 1
failed
win32 Test

[----------] Global test environment tear-down
[==========] 173 tests from 5 test cases ran. (919337 ms total)
[ PASSED ] 172 tests.
[ FAILED ] 1 test, listed below:
[ FAILED ] MiscTests.ExportRestorePlaylist

1 FAILED TEST
ERROR: Job failed: exit code 1
failed
asan-ubsan Test

[----------] Global test environment tear-down
[==========] 173 tests from 5 test cases ran. (606518 ms total)
[ PASSED ] 172 tests.
[ FAILED ] 1 test, listed below:
[ FAILED ] MiscTests.ExportRestorePlaylist

1 FAILED TEST
ERROR: Job failed: exit code 1
failed
linux Test

[----------] Global test environment tear-down
[==========] 173 tests from 5 test cases ran. (661918 ms total)
[ PASSED ] 172 tests.
[ FAILED ] 1 test, listed below:
[ FAILED ] MiscTests.ExportRestorePlaylist

1 FAILED TEST
ERROR: Job failed: exit code 1