Backport core PRs to stable (#7892)

* update back-references more aggressively after answering from cache (#7578)

* Flush keyfiles. Resolves #7632 (#7868)

* Fix wallet import (#7873)

* rpc: generate new account id for imported wallets

* ethstore: handle duplicate wallet filenames

* ethstore: simplify deduplication of wallet file names

* ethstore: do not dedup wallet filenames on update

* ethstore: fix minor grumbles

* parity-version pr reopen (#7136)

* parity-version module split from util

removed unused util deps and features

trigger buildbot again

only kvdb links rocksdb

snappy linker issues

* rm snappy

* fixed old version imports

* Move updater metadata to Cargo.toml of parity-version. (#7832)

* Update version.

* Bump parity version.

* Fix version.

* Fix compilation.