fix: Consider the emails where in-reply-to header has multiple values (#7715)

- Return the first message id for now to avoid the errors and subsequently missing the message.
- Use .last instead of .first to avoid expensive query.
- Fix array response in response bot.

Fixes:  https://linear.app/chatwoot/issue/CW-2358/activerecordstatementinvalid-pgdatatypemismatch-error-argument-of-and

spec/fixtures/files/multiple_in_reply_to.eml

@@ -0,0 +1,18 @@
+From: Sony Mathew <Sony@chatwoot.com>
+Mime-Version: 1.0 (Apple Message framework v1244.3)
+Content-Type: multipart/alternative; boundary="Apple-Mail=_33A037C7-4BB3-4772-AE52-FCF2D7535F74"
+Subject: Discussion: Let's debate these attachments
+Date: Tue, 20 Apr 2020 04:20:20 -0400
+In-Reply-To: <4e6e35f5a38b4_479f13bb90078171@small-app-01.mail>
+  <4e6e35f5a38b4_479f13bb90078131@small-app-01.mail>
+To: "Replies" <replies@example.com>
+References: <4e6e35f5a38b4_479f13bb90078178@small-app-01.mail>
+Message-Id: <0CB459E0-0336-41DA-BC88-E6E28C697DDB@chatwoot.com>
+X-Mailer: Apple Mail (2.1244.3)
+
+--Apple-Mail=_33A037C7-4BB3-4772-AE52-FCF2D7535F74
+Content-Transfer-Encoding: quoted-printable
+Content-Type: text/plain;
+  charset=utf-8
+
+Let's talk about these images