fish: Command history improvements (#4672)

This change provides the following improvements:

- Changes the view of the command history list, so that the script no longer depends on perl for performance.
- Enables syntax color highlighting on fish v4.3.3 and newer.
- Provides a preview window with the selected commands, and expanded view of the highlighted command if available.
- Improves the delete functionality, by successfully handling very large numbers of selected commands.
- Inserts commands in their formatted form with `<Alt-Enter>`.

---

* fish: Change history list view

The view of the command history is changed, so that no manipulation is
performed on the output of history command: The history item count
number is replaced by the Unix time of the command, multi-line display
is disabled and line wrapping is enabled by default. On fish v4.3.3
and newer, the use of ANSI color codes for syntax highlighting is now
possible, while the script no longer depends on perl for performance.

Fixes #4661

* fish: Reformat selected history commands with ALT-ENTER

* Add $FZF_WRAP environment variable

The variable is set when line wrapping is enabled. It has the value
`word` if word wrapping mode is set, otherwise it has the value `char`.

* fish: Add command history preview

The preview shows the highlighted command and any selected commands,
after first being formatted and colorized by fish_indent. The timestamp
of the highlighted command in the preview is converted to strftime
format "%F %a %T" if the date command is available.

The preview is hidden on start, and is displayed if more than 100
columns are available and one of the following conditions are met:
- The highlighted item doesn't completely fit in list view (line
wrapping is enabled for the preview and is now disabled for the list).
- The highlighted item contains newlines (multi-line commands or
strings).
- The highlighted item contains chained commands in a single line, that
can be broken down by the formatter for cleaner view.
- One or more commands are marked as selected.

* fish: Handle deletion of large number of selected history entries

* fish: Change wrapping options for the preview-window

test/test_shell_integration.rb

@@ -138,7 +138,7 @@ module TestShell
     tmux.send_keys 'C-r'
     tmux.until { |lines| assert_equal '>', lines[-1] }
     tmux.send_keys 'foo bar'
-    tmux.until { |lines| assert_includes lines[-4], '"foo' } unless shell == :zsh
+    tmux.until { |lines| assert_includes lines[-4], '"foo' } if shell == :bash
     tmux.until { |lines| assert lines[-3]&.match?(/bar"␊?/) }
     tmux.send_keys :Enter
     tmux.until { |lines| assert lines[-1]&.match?(/bar"␊?/) }
@@ -1020,15 +1020,23 @@ class TestFish < TestBase
     tmux.send_keys 'echo "bar', :Enter, 'foo"', :Enter
     tmux.prepare
     tmux.send_keys 'C-l', 'C-r'
+    offset = -6
     block = <<~BLOCK
       echo "foo
       bar"
       echo "bar
       foo"
     BLOCK
+    if shell == :fish
+      offset = -4
+      block = <<~FISH
+        echo "foo␊bar"
+        echo "bar␊foo"
+      FISH
+    end
     tmux.until do |lines|
       block.lines.each_with_index do |line, idx|
-        assert_includes lines[-6 + idx], line.chomp
+        assert_includes lines[idx + offset], line.chomp
       end
     end
     tmux.send_keys :BTab, :BTab