feat: link to add events from agenda to google calendar

[rabarbra]

[rabarbra]

I need to add an item to setting to enable / disable this feature.

[FreekBes]

For adding a setting, please take a look at the following commits / releases:
https://github.com/FreekBes/improved_intra_server/releases/tag/v3.2.0 - adding a setting to the database
FreekBes/improved_intra_server@fe0453c - adding a setting to the back-end (setting up a back-end dev environment is rather difficult due to not having set up a Dockerfile yet - it's on my todo list)
a7f746f - adding a default value to the extension
58ffd8e - retrieving the value set from the storage

I'll try to take a look at and test your other pull requests soon. Thanks a lot for your contributions.

Speaking of contributions, through Improved Intra it's possible to get a "Contributor" title added to your Intra profile, though it is only visisble for Improved Intra users. If you would like to have this title, please let me know. Sadly it cannot be equipped like any other Intra title - it is hardcoded into the extension.

[FreekBes]

I've set up a branch that runs the Improved Intra back-end server in a Docker container. This should make development and testing of the to-be-added setting easier.

However, I could also implement it myself. Let me know if you want me to.

[rabarbra]

Thank you very much for the comments and for the backend  branch. I don't mind doing this backend part myself, but a little bit later - now I have to work on another project for a while.

As for the suggestion to add a "Contributor" title to my intra profile - I don't mind, it would be great. My intra name is psimonen.