ripgrep: add --auto-hybrid-regex flag

This flag, when set, will automatically dispatch to PCRE2 if the given
regex cannot be compiled by Rust's regex engine. If both engines fail to
compile the regex, then both errors are surfaced.

Closes #1155

complete/_rg

@@ -112,6 +112,10 @@ _rg() {
     '--hidden[search hidden files and directories]'
     $no"--no-hidden[don't search hidden files and directories]"
 
+    + '(hybrid)' # hybrid regex options
+    '--auto-hybrid-regex[dynamically use PCRE2 if necessary]'
+    $no"--no-auto-hybrid-regex[don't dynamically use PCRE2 if necessary]"
+
     + '(ignore)' # Ignore-file options
     "(--no-ignore-global --no-ignore-parent --no-ignore-vcs --no-ignore-dot)--no-ignore[don't respect ignore files]"
     $no'(--ignore-global --ignore-parent --ignore-vcs --ignore-dot)--ignore[respect ignore files]'