Improve error messages with file paths in remote upload

This commit enhances error messages in the remote upload functionality by including specific file paths. It updates both the implementation in remote.go and the corresponding tests in remote_test.go to provide more detailed error information.

add condition test with sudo

add test for prepScript to ensure the cleanup was invoked

Bump github.com/hashicorp/go-retryablehttp from 0.7.6 to 0.7.7

Bumps [github.com/hashicorp/go-retryablehttp](https://github.com/hashicorp/go-retryablehttp) from 0.7.6 to 0.7.7.
- [Changelog](https://github.com/hashicorp/go-retryablehttp/blob/main/CHANGELOG.md)
- [Commits](hashicorp/go-retryablehttp@v0.7.6...v0.7.7)

---
updated-dependencies:
- dependency-name: github.com/hashicorp/go-retryablehttp
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>

Merge pull request #197 from umputun/register-across-tasks

Allow registered vars to be populated across tasks

Fix handling of user set on the task level (#193)

* Fix incorrect handling of task-level user #192

The change eliminates setting the default task.User on the config level,
and moves this responsibility to the runner. Now the runner explicitly
checks the presence of task.User and passes it in.

In addition, runTaskOnHost sets the passed user into activeTask
(a copy of the task used later on). This was done to be able to know what
the actual user is. Currently, the only use is in setting SPOT_REMOTE_USER,
however, it can also be used in any place that needs to know the active remote user.

* update man and site

* add a test for user name set on task level

update site docs

update release ci to 1.22

update playbook schema for #180

Merge pull request #171 from olegmlsn/no_default_key

Do not select the default key with --ssh=agent