[RSDK-8891] - Remove malformed filenames from concat operation

[seanavery]

Description

Simple pr to remove erroneous files from file lookup and storage matcher for concats.

For example .DS_STORE files on macos will now be ignored.

Test

• manually tested with .DS_STORE file ✅
• added test video file with incorrect file name ✅

[randhid]

thanks for adding a test file, I don't see any changes to the tests but assuming it's being tests somehow?

[seanavery]

@randhid

thanks for adding a test file, I don't see any changes to the tests but assuming it's being tests somehow?

yes, it is implicitly tested by both save and fetch tests. it does not fail with bad file name in storage dir.