"Fixes" `MANIFEST.MF` newline/comma bug

[maxkratz]

Before merging this PR, the manifest mechanism in emoflon-core produced invalid MANIFEST.MF files in some of the test cases.

• Our implementation broke lines that exceeded the 72 bytes per line limitation.
• The manifest reader of the standard java implementation read multiple lines as separate entries.
• Our implementation separated the "entries" with , -> This broke the files in some situations.

Example:

...
Require-Bundle: org.emoflon.ibex.common,org.emoflon.ibex.gt,org.emoflon.ibex.
 ,patternmodel,org.emoflon.ibex.gt.democles,org.emoflon.ibex.gt.hipe
...

This PR "fixes" this behavior because each entry will be represented in its own line. However, there is the possibility that this causes an invalid MANIFEST.MF file if the complete value of one entry exceeds the 72 bytes per line limit, e.g., org.emoflon.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa. IMO, this is more desirable compared to the previous implementation that broke multiple (existing) files repeatedly.

Tested with:

• [x] eMoflon::IBeX test workspace
• [x] GIPS test workspace
• [x] iflye test suite