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##### SUMMARY
Add comment_start_string and comment_end_string to template plugin.

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
template

##### ADDITIONAL INFORMATION
In some situation, we need to change comment behavior of template plugin, for an example macros in Zabbix is like {#MACRO}.

<!--- Paste example playbooks or commands between quotes below -->
```yaml
- name: Render a template with "comment_start_string" set to [#
  template:
    src: template.xml.j2
    dest: template.xml
    comment_start_string: "[#"
    comment_end_string: "#]"
```

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- The string marking the end of a block.
    type: str
    default: '%}'
    version_added: '2.4'
  variable_start_string:
    description:
    - The string marking the beginning of a print statement.
    type: str
    default: '{{'
    version_added: '2.4'
  variable_end_string:
    description:
    - The string marking the end of a print statement.
    type: str
    default: '}}'
    version_added: '2.4'
  trim_blocks:
    description:
    - Determine when newlines should be removed from blocks.
    - When set to C(yes) the first newline after a block is removed (block, not variable tag!).
    type: bool
    default: yes
    version_added: '2.4'
  lstrip_blocks:
    description:
    - Determine when leading spaces and tabs should be stripped.
    - When set to C(yes) leading spaces and tabs are stripped from the start of a line to a block.
    - This functionality requires Jinja 2.7 or newer.
    type: bool
    default: no