Ensure vaadin-compatibility-client is OSGi compatible

[Legioth]

According to https://vaadin.com/forum/thread/17756874/vaadin-7-to-8-migration-vaadin-compatibility-client-not-osgi-compatible, the vaadin-compatibility-client is not OSGi compatible. Based on a quick look at MANIFEST.MF, it does indeed seem like the customary OSGi entires are missing.

[TatuLund]

I managed to get OSGi Vaadin portlet to work with Liferay 7 (ref the documentation https://vaadin.com/docs/v8/framework/portal/portal-osgi.html ) but in that experiment ) did use vaadin-compatibility-client-compiled instead. So probably manifest for it is correct. Need to cross check.

[stale[bot]]

Hello there!

We are sorry that this issue hasn't progressed lately. We are prioritizing issues by severity and the number of customers we expect are experiencing this and haven't gotten around to fix this issue yet.

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[chrisnaan]

I've created PR#12422 to add the OSGI entries to the manifest.