Fixes https://codeberg.org/forgejo/forgejo/issues/4417 by adding a conditional branch to the `head_opengraph` template to match wiki pages. I tried to be consistent with the other types:
- `og:title` is the wiki page title
- `og:url` is built via `{{AppUrl}}{{.Link}}` like it is done for commit and file views. This has the caveat of doubling the slash (see test below). Should we `{{trimSuffix "/" AppUrl}}` to remove this, if sprig is available?
- `og:description` is the repository description to match GH behaviour. Also, the first sentences of the page might not be descriptive enough. Should we prefix the repo description with the repo name?
- `og:type` and `og:image` are common
Added a `TestOpenGraphProperties` integration test using existing fixtures. Coverage is not 100% but can be improved later.
## Output on a test repo
```html
<meta property="og:title" content="Project architecture">
<meta property="og:url" content="http://localhost:3000//xvello/wiki-test/wiki/Project-architecture">
<meta property="og:description" content="description for a test project">
<meta property="og:type" content="object">
<meta property="og:image" content="http://localhost:3000/avatars/3dd4d1e4eef065d1b4ad4bdb081ab6e7">
```
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/4427
Co-authored-by: Xavier Vello <xavier.vello@gmail.com>
Co-committed-by: Xavier Vello <xavier.vello@gmail.com>
- It was noticed [in the Forgejo matrix channel](https://matrix.to/#/!qjPHwFPdxhpLkXMkyP:matrix.org/$vk78UR0eFCwQMDMTZ7-DWjMVB_LIAwHW6SkjhEcGkQQ?via=matrix.org) that the generation of the Forgejo project contributor stats was taking quite a while on codeberg.org. This was continued with the fact that a few moments later it was once again generating them again; it seemed like they weren't being cached while they were.
- The problem was that the cache TTL is hardcoded to ten minutes and not to the configured TTL. This patch changes that by using the configured TLL for the contributor cache, as this is a computationally heavy operation and should be cached for as long as possible for a good user experience. This doesn't impact the accuracy of this feature because the commit ID of the default branch is used as a cache key.
- Also changed in this patch, is that errors aren't cached and are instead being logged, this is more helpful to the administrator. For the user essentially nothing changed on this side, the contributor stats just looks like it's loading indefinitely.
- Realistically, testing this isn't possible, as the cache library Forgejo currently uses doesn't expose the TTL or expiration time of a key. Manually testing this behavior is quite lengthy, as one of the steps would need to be "wait for ten minutes" and describe how you can notice the data was cached or was just generated, and because you could use different types of cache, it will be quite hard to write down how you could check the TTL of a key for a particular cache (I'm not even sure it's even possible for some).
