Allow Passing Additional Flags to Restic

[sebt3]

Description

QNAP QuObjects is an "s3 compliant" service on QNAP nas machine. It can be configured as using tls, but it use a self-signed certificate. Restic can use it but requires "--insecure-tls" argument to use it. Yet k8up doesn't allow to pass that argument to restic. It can also but used as http, but then restic use a minio compatibility mode which doesnt suit QuObjects and restic fail with "The Content-MD5 you specified was invalid".

Additional Context

No response

Logs

using tls:
1.6723221876801217e+09  INFO    k8up.restic.restic.RepoInit.restic.stderr       Fatal: create repository at s3:https://s3.rennes.home:8443/solidite failed: client.BucketExists: Get "https://s3.rennes.home:8443/solidite/?location=": x509: certificate is not valid for any names, but wanted to match s3.rennes.home

using plain http:
1.6723222329661973e+09  INFO    k8up.restic.restic.RepoInit.restic.stderr       Fatal: create key in repository at s3:http://s3.rennes.home:80/solidite failed: client.PutObject: The Content-MD5 you specified was invalid

Expected Behavior

Using restic command-line it works :

export RESTIC_REPOSITORY="s3:https://s3.rennes.home:8443/solidite" restic init --insecure-tls created restic repository 493e88aa9c at s3:https://s3.rennes.home:8443/solidite ....

Please provide a way to propagate that --insecure-tls to restic

Acceptance Criteria

• Add a new field "additionalResticArgs" to all jobs and the schedule object ** These flags will be passed to all restic calls within K8up ad verbatim
• Document this new feature ** It should be clearly marked as an advanced configuration as we can't guarantee the correctness of all passed restic flags

Steps To Reproduce

No response

Version of K8up

v2.5.2

Version of Kubernetes

v1.25.3+k3s1

Distribution of Kubernetes

k3s