Metadata Bundle zip file's order of processing is not as expected

[himeshr]

Describe the bug
The un-tampered Metadata Bundle zip file is processed in the order of the files inserted while generating the bundle, which is as per code in ImplementationController.export().
If the bundle is tampered, for example to remove any forms or concepts, then the sequence of processing of bundle files is unknown.
This is contrary to expectations as per the ordering specified in BundleZipFileImporter.fileSequence code.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'App Designer' for a test org with lot of metadata
2. Download bundle
3. Unzip the Bundle and remove the forms folder and concepts file
4. Zip the content and then upload it back into same test org
5. Observe the logs, the sequence of bundle files processed is different from what is specified in BundleZipFileImporter.fileSequence.
6. Instead if we were to upload an untampered bundle zip file, then the bundle files are processed in the oder of the bundle generation, which is as per ImplementationController.export().

Expected behavior
On uploading Metadata zip file bundle, files should always be processed in the order as per BundleZipFileImporter.fileSequence.
Irrespective of whether its tampered with or not.

Additional context
Issue found during debug of #559 (comment)

Developer Checklist
Developer fixing the bug should fill this checklist.

• Does the fix require extensive regression testing?
• Are you mentioning the required scenarios that could be affected?