Building ZIO Shield cache on first run in metals

[vovapolu]

It seems on the first run (I mean before any compilation of the project) metals doesn't generate SemanticDb files before ZIO Shield runs or ZIO Shield doesn't see those files or ZIO Shield runs too early not waiting for SemantidDb. On the second run, after restarting metals server or after reopening the editor, ZIO Shield reads necessary SemanticDb files just fine.