TiKV-BR v1.1.0

Key features & improvements

1. Support Amazon S3 as storage when backup and restoration. See User Guide.
2. Support backup and restoration with key range. See User Guide.
3. Support backup and restoration for TLS enabled TiKV cluster. See User Guide.
4. Support backup and restoration for v5.x.x TiKV cluster. See User Guide.
5. Support rate limit during backup and restoration. See User Guide.
6. Improve code coverage of unit tests and integration tests.

What's Changed

• [close #217] Add BR unit test coverage statistics by @haojinming in #218
• [close #220] TiKV-BR support key range by @haojinming in #221
• [close #229] Add integration test coverage report for TiKV-BR by @haojinming in #230
• [close #227] Update BR readme by @haojinming in #228
• [close #235] Support TLS connection for TiKV-BR by @haojinming in #236
• [close #239] Add gcttl and range in readme by @haojinming in #240
• [close #263] Fix br docker build by @haojinming in #264
• [close #267] Fix restore ratelimit by @haojinming in #268
• [close #231] TiKV-BR support v5.x.x by @haojinming in #282
• [close #305] Fix supported version in tikv br README by @haojinming in #306