refactor: use insta for tests snapshots

[aljazerzen]

When changing the interface, tests had to be updated using following error messages to find the mismatch:

---- ui::draw_blocks::tests::test_draw_blocks_whole_layout_long_name stdout ----
thread 'ui::draw_blocks::tests::test_draw_blocks_whole_layout_long_name' panicked at src/ui/draw_blocks.rs:3192:17:
assertion `left == right` failed
  left: "n"
 right: " "

I've now added insta, that defines tests like this:

        assert_snapshot!(
            text, @r#"
            ╭──────────╮
            │▶ pause   │
            │  restart │
            │  stop    │
            │  remove  │
            ╰──────────╯
            "#
        );

... and produces error messages like this:

---- ui::draw_blocks::tests::test_draw_blocks_commands_panel_selected_color stdout ----
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Snapshot Summary ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Snapshot: draw_blocks_commands_panel_selected_color
Source: src/ui/draw_blocks.rs:1274
─────────────────────────────────────────────────────────────────────────────────────────────────────
Expression: text
─────────────────────────────────────────────────────────────────────────────────────────────────────
-old snapshot
+new results
────────────┬────────────────────────────────────────────────────────────────────────────────────────
    0     0 │ ╭──────────╮
    1     1 │ │▶ pause   │
    2     2 │ │  restart │
    3     3 │ │  stop    │
    4       │-│  remove  │
          4 │+│  delete  │
    5     5 │ ╰──────────╯
────────────┴────────────────────────────────────────────────────────────────────────────────────────
To update snapshots run `cargo insta review`
Stopped on the first failure. Run `cargo insta test` to run all snapshots.