segregated indexer: handler trait and migrate snapshot_objects table #76313

Job	Run time
diff	7s
license-check	1m 4s
test (ubuntu-ghcloud)	26m 22s
move-auto-formatter-ci-test	0s
simtest	15m 34s
test-extra (ubuntu-ghcloud)	10m 19s
windows-build (windows-ghcloud)	8m 31s
clippy	3m 16s
move-test	0s
test	0s
cargo-deny (advisories, licenses, bans, ...)	34s
rustfmt	22s
cutting a new execution layer	1m 18s
test-extra	0s
	1h 7m 27s

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