[ticket/12376] Add template events viewtopic_body_polls

[PayBas]

I propose 3 template events:

1: EVENT viewtopic_body_poll_question_prepend

It would be the equivalent of viewtopic_topic_title_prepend, and will allow us to use prefixes, or better yet, icons. It will allow us to use code like:
<h2><span class="<!-- IF S_CAN_VOTE and L_POLL_LENGTH -->poll-icon-timer<!-- ELSEIF S_CAN_VOTE -->poll-icon-open<!-- ELSE -->poll-icon-closed<!-- ENDIF -->">{L_VIEW_TOPIC_POLL}</span>....</h2>

2: EVENT viewtopic_body_poll_fieldset_prepend
Having control of the poll fieldset can have advantages in case we want to add extra functionality, buttons or create wrapping containers.

3: EVENT viewtopic_body_poll_fieldset_prepend
The counter-part to the previous one

PHPBB3-12376

[nickvergessen]

please also create append for the title

[PayBas]

Ok, I just assumed we weren't doing that because the other <h2> blocks don't have an append either

[nickvergessen]

@PayBas if you prepend something, you should be able to append aswell ;)

[PayBas]

@nickvergessen how true, sadly not always the case ;)

I'll update it.

[nickvergessen]

I don't like fieldset in the event name, it's a bit arbitrary.
I'd suggest to move it inside the loop and call it <!-- EVENT viewtopic_body_poll_option_before -->. This also makes it more powerful

You can still use the event as you wanted to, by wrapping your own template with:
<!-- IF poll_option.S_FIRST_ROW -->

[PayBas]

That's pretty smart ;), although it's not exactly the same, as it will not include the poll buttons. But I guess we can work around that.

[nickvergessen]

Please rebase onto develop-ascraeus, so the event tests are run