Added stream_post_policy to the streaminfo view

[mounilKshah]

What does this PR do?
This PR contains commit which add the stream_post_policy to the streaminfo view. Test case for the same have been added under tests/ui_tools/test_popups.py
Partial fix for #1119.

Link to discussion on chat.zulip.org:
#zulip-terminal>Adding elements to stream info

Tested?

• Manually
• Existing tests (adapted, if necessary)
• New tests added (for any new behavior)
• Passed linting & tests (each commit)

Commit flow

• Contains code for adding stream_post_policy and the updated test_popup_height function

Visual changes

Before the commt:

After the commit:

[neiljp]

@mounilKshah Good start, with lots of overlap with the other PR.

One thing we can do in these situations is, where appropriate, extract things like functions we use (or will use) in separate earlier commits in one of these PRs. If we're only adjusting existing code with no behavioral change, this is a refactor: commit. Myself or someone else with merge rights can push a few commits using git cherry-pick, making multiple PRs which depend on it easier to handle as they can both then be rebased against the new main branch. Or, of course, you could just make another PR for that and rebase once that is merged.

[neiljp]

This is what I meant about the start of the other PR code, where there is something simpler.

[mounilKshah]

I will go through it once again and make the required changes.

[neiljp]

@mounilKshah This looks close 👍

At some point I think it'd be good to migrate to modern versions when we get the data itself like we do with some other data, but this version works well for now.

I'm unclear if the final part of #1119 is functional on the server at this point (or will be replaced by a new implementation instead), but I suspect this can be extracted into a separate issue once we know what's happening there.

As a follow-up to this it might be useful to discuss if we want to group/combine the related stream visibility properties to make it clearer.
(we could also add a way to copy a link to the stream for web usage)

[mounilKshah]

I'm unclear if the final part of #1119 is functional on the server at this point (or will be replaced by a new implementation instead), but I suspect this can be extracted into a separate issue once we know what's happening there.

Putting it under a separate issue seems to be a good idea to me. As you had mentioned here, we can have a separate section for the user details in the stream. Apart from the user role, we can also add details like average number of messages sent by user in the stream, number of topics the user has posted on (out of total topics in the stream), etc.

As a follow-up to this it might be useful to discuss if we want to group/combine the related stream visibility properties to make it clearer. (we could also add a way to copy a link to the stream for web usage)

This can be a good addition to the stream info!

[neiljp]

@mounilKshah While I think in principal we could improve these tests, I'll be happy to merge my local slightly adjusted version if we can agree on the text for the 3 policy value, as per my message in the stream.

[neiljp]

@mounilKshah Thanks for this! Merging now after some minor commit text adjustments 🎉