Use Hyperlink widget for links in message info popup.

[theViz343]

What does this PR do, and why?

This PR introduces the Hyperlink widget for message links in message information popups. This solves the issue of long urls being force-wrapped which results in them not being clickable from ZT.

Outstanding aspect(s)

• The focus on the currently selected link is a bit off. It doesn't cover the link.

External discussion & connections

• [x] Discussed in #zulip-terminal in Hyperlink support using OSC-8 escape sequences
• [ ] Fully fixes #
• [x] Partially fixes issue #1368
• [ ] Builds upon previous unmerged work in PR #
• [ ] Is a follow-up to work in PR #
• [ ] Requires merge of PR #
• [ ] Merge will enable work on #

How did you test this?

• [x] Manually - Behavioral changes
• [x] Manually - Visual changes
• [ ] Adapting existing automated tests
• [ ] Adding automated tests for new behavior (or missing tests)
• [ ] Existing automated tests should already cover this (only a refactor of tested code)

Self-review checklist for each commit

• [x] It is a minimal coherent idea
• [x] It has a commit summary following the documented style (title & body)
• [x] It has a commit summary describing the motivation and reasoning for the change
• [ ] It individually passes linting and tests
• [ ] It contains test additions for any new behavior
• [ ] It flows clearly from a previous branch commit, and/or prepares for the next commit

Visual changes

[Subhasish-Behera]

Hey @theViz343 ,I am getting the error

 File "/home/subhasishbehera/zulip-terminal/zulipterminal/ui_tools/buttons.py", line 11, in <module>
    import urwidgets
ModuleNotFoundError: No module named 'urwidgets'

[neiljp]

@Subhasish-Behera If you're using make then run that and it should check you have the required dependencies, or reinstall the editable zt package over the top (if not using make).

@theViz343 It would be useful to have the dependency change visible as a separate small commit, as we do when we change other requirements.