JSON-formatted log files #3076

Tests

• ✅ key.core.testgen:test (13 succeeded)
• ✅ key.core:test (2927 succeeded, 102 skipped)
• ✅ key.core:testProveRules (196 succeeded)
• ✅ key.core:testRunAllFunProofs (47 succeeded)
• ✅ key.core:testRunAllInfProofs (30 succeeded)
• ✅ key.removegenerics:test (45 succeeded)
• ✅ key.util:test (134 succeeded)
• ✅ recoder:test (14 succeeded, 15 skipped)