Proxmox remote pct connection (#8424)

* First Revision (squashed)
Co-authored-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>

* Second Revision (squashed)

* implement data_in

* Removed quot()
There is no need for quoting, exec_command gets the command already quoted with shell from Ansible

* Use shell from self._shell

* Improved error handling

* updated docs

* Use Int for Container ID

* Updated docs to include detailed description for non root usage

* Fix ansible_user var in example

* Fix become method
We need to differentiate between become method used in Proxmox and the one inside the container.

* Implement review findings
- f-Strings
- lower() when input
- yaml indent
- consistent quotes
- use to_text()
- Enhanced examples
- Ansibullbot findings

* remove ssh cache

* Ensure we delete the tempfile

* use octal mode

* Use FileLock().lock_file

* ansibullbot findings

* refactor _connect()

* Update plugins/connection/pct_remote.py

Co-authored-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Felix Fontein <felix@fontein.de>

* renamed plugin to proxmox_pct_remote

* Use ansible.builtin.ping as example

* added unit tests

* fixed bugs in close()

* catch invalid host key

* test invalid host key

* Added integration test

* cleanup

* setup test via ansible

* Revised notes based on review feedback

* Review findings
Co-authored-by: Felix Fontein <felix@fontein.de>

* gather_facts hint in example

* Update tests/integration/targets/connection_proxmox_pct_remote/aliases

Co-authored-by: Felix Fontein <felix@fontein.de>

* Fix FreeBSD, deactivate macOS

* Test and Fix: Hang on copy with empty content

---------

Co-authored-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>
Co-authored-by: Felix Fontein <felix@fontein.de>

tests/integration/targets/connection_proxmox_pct_remote/plugin-specific-tests.yml

@@ -0,0 +1,32 @@
+---
+# Copyright (c) Ansible Project
+# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+- hosts: "{{ target_hosts }}"
+  gather_facts: false
+  serial: 1
+  tasks:
+    - name: create file without content
+      copy:
+        content: ""
+        dest: "{{ remote_tmp }}/test_empty.txt"
+        force: no
+        mode: '0644'
+
+    - name: assert file without content exists
+      stat:
+        path: "{{ remote_tmp }}/test_empty.txt"
+      register: empty_file_stat
+
+    - name: verify file without content exists
+      assert:
+        that:
+          - empty_file_stat.stat.exists
+        fail_msg: "The file {{ remote_tmp }}/test_empty.txt does not exist."
+
+    - name: verify file without content is empty
+      assert:
+        that:
+          - empty_file_stat.stat.size == 0
+        fail_msg: "The file {{ remote_tmp }}/test_empty.txt is not empty."