change system message text on new stream & new space

[elatif2020]

Change the text for the system messages (appearing in the home discussion) as follows:
For a new space:
The $spaceName space was created by $userName

For a new stream (discussion\proposal):
$streamName was created by $userName

We have a separate BE ticket

[budnik9]

@elatif2020 What about space editing?

Should the system message text be changed there?

[elatif2020]

@elatif2020 What about space editing?

Should the system message text be changed there?

This is an extension of this ticket 🙃 🙏
But yes, let's change it to:
This space's info was edited by $userName

[NoamQA]

to be tested after #2281 fixed