[InstallSSHKeyV0] Added config editing

[egor-bryzgalov]

Task name: InstallSSHKeyV0

Description:

• Feature was Implemented which allows to add entry to SSH config file. It can be useful for storing different SSH options for each remote server.
• Changed known_hosts handling behavior. Entries will be appended if the task is invoked multiple times instead of overwriting the whole file.
• Public key file is now created to avoid errors while deleting keys from agent in the post-job step.

Documentation changes required: (Y/N) Yes

Added unit tests: (Y/N) No

Attached related issue: (Y/N) #13283

Checklist:

• Task version was bumped - please check instruction how to do it
• Checked that applied changes work as expected

[sdobrodeev]

LGTM, thanks!

[damccorm]

LGTM

[anatolybolshakov]

LGTM, thanks!