* backup,restore: work on progress to fix a bug that causes --checksum flag won't work properly.

Some code of backup and restore ignored the flag (a.k.a. config.Checksum), so when checksum is disabled, we will face failure.

* backup: backup will report total bytes and kvs when checksums check disabled.

Some code of backup and restore ignored the flag (a.k.a. config.Checksum), so when checksum is disabled, we will face failure.

* backup: backup will report total bytes and kvs when checksums check disabled.

Some code of backup and restore ignored the flag (a.k.a. config.Checksum), so when checksum is disabled, we will face failure.

* backup: add log to ChecksumMatches and new version of FastChecksum.

Some of log has been lose. They are in ChecksumMatches now.

* restore: restore could find non-checksum tables and skip them automatically.

for backup, ChecksumMatches returns error now.

* misc: add document for Table::NoChecksum.

* backup: omit checksum progress bar when user specify `--checksum=false`.

* backup: `CopyMetaFrom` overrides original `client.Schemes` instead of append at its end.

* backup: refactor about checksum logic, fix a bug.

the bug would cause: when multi tables are backup, the metadata contains only one table.

* backup: do some lints.

* backup,restore: do some refactor so that cyclomatic complexity won't be too large.

* misc: don't use underscore on receiver.

* backup: print "quick checksum success" message per table.

...to make br_full_index happy!

* backup: refactor a MinInt pattern.

* backup: Apply suggestions from code review

Co-Authored-By: kennytm <kennytm@gmail.com>

Co-authored-by: 3pointer <luancheng@pingcap.com>
Co-authored-by: kennytm <kennytm@gmail.com>

* create with info during incremental restore

* add test

* fix log

* address comment

* fix ci

* address commemnt

* redirect kvproto

Signed-off-by: Yi Wu <yiwu@pingcap.com>

* pass sse_kms_key_id

Signed-off-by: Yi Wu <yiwu@pingcap.com>

* fix hound

Signed-off-by: Yi Wu <yiwu@pingcap.com>

* update kvproto

Signed-off-by: Yi Wu <yiwu@pingcap.com>

* go mod tidy

Signed-off-by: Yi Wu <yiwu@pingcap.com>

Co-authored-by: kennytm <kennytm@gmail.com>

…gcap#246)