support rclone options in backup and restore cr

[DanielZhangQD]

What problem does this PR solve?

Fix #2270

What is changed and how does it work?

Support specifying rclone options in the backup and restore CR which can be used during backup and restore with mydumper and lightning.
For the issue in #2270, we need to set --ignore-checksum option for rclone, for detail, please check the doc.
CR example:

apiVersion: pingcap.com/v1alpha1
kind: Backup
metadata:
  name: test31-lt-07
  namespace: test31
spec:
  from:
    host: test31-tidb
    port: 4000
    user: root
    secretName: backup-secret
  s3:
    provider: aws
    region: us-west-2
    secretName: s3-secret-aws
    bucket: danz-backup10/lt07
    options:
    - --ignore-checksum
  storageClassName: local-storage
  storageSize: 1Gi

Check List

Tests

• Manual test (add detailed scripts or steps below)
• backup, restore, scheduled backup, clean with s3 encryption disabled
• backup, restore, scheduled backup, clean with s3 aes-256 encryption
• backup, restore, scheduled backup, clean with s3 aws-kms encryption

Code changes

• Has Go code change

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Does this PR introduce a user-facing change?:

Support `rclone` options in Backup and Restore CR

[cofyc]

why not use string slice?

[Yisaer]

I'm not sure whether expose args by a string is ok to users. Can we import the rclone configFlag as rcloneConfig in the Backup and Restore Spec like tidb/tikv/pd config

[DanielZhangQD]

That would be too much config fields. Since mydumper+lightning is not our focus already, I think it's OK to support like this.
I will change it to string slice.

[Yisaer]

I think we don't have to set all the configuration of rclone, just use the configuration we need.

[onlymellb]

LGTM

[DanielZhangQD]

@cofyc comments addressed, PTAL.

[DanielZhangQD]

/merge

[sre-bot]

/run-all-tests

[sre-bot]

@DanielZhangQD merge failed.

[DanielZhangQD]

/merge

[sre-bot]

/run-all-tests

[sre-bot]

cherry pick to release-1.1 in PR #2326