[MBL-1431] Fix post button compressing

[ifosli]

📲 What

Update the comment "post" button to no longer have a dynamic size by setting compression resistance and content hugging priority to required.

👀 See

Jira

Before 🐛	After 🦋	After Large Text

♿️ Accessibility

Since I got rid of the max button size in favor of sticking with the content size, I did check what happens for largest accessible size in spanish and the button looks okay

✅ Acceptance criteria

• This happens at random, but I also managed to consistently repro by starting to type a comment in the main project comments, opening comment replies and start typing a comment there, navigate back to main project comments to keep typing (and post button disappears). Now it should no longer disappear.
• Posting experience for large font sizes is no worse

[scottkicks]

nice!