Feature/escalate via ivr

[Lakshmi2107]

Description:
Currently, GoAlert supports alert escalation via web app only and IVR/SMS doesn't have the same options for the users to escalate the issues immediately. We can have escalated options for alerts like ack and close alert actions in the IVR and SMS(text). 4 is used to ack and 6 is used to close the alert. Probably, 5 can be used to escalate the alert to the next level. For SMS(Text), 1a - ack, 1c-close and 1e-escalate alert.

Which issue(s) this PR fixes:
Fixes #2775

Describe any introduced user-facing changes:
In Voice calls and SMS, we will have an additional message saying press 5 to escalate and {code}e to escalate, respectively.

We need to think about introducing an already escalated option.

[mastercactapus]

This is in a fairly good state. However, it may be good to make some adjustments for escalations to detect when an alert is already closed since, without it, this will reply "alert escalated" even after the alert is closed.

I'll open a separate PR for fixing that, but for this PR:

• The Receive handler: it's missing the escalation case, so this doesn't work yet when I tested locally. It should be the same as ReceiveSubject
• The reply message should probably be "escalation requested" since escalations are always handled async

[Lakshmi2107]

@mastercactapus thanks for ur comments. I have pushed the changes. Please review.

[mastercactapus]

@Lakshmi2107 hey, I had a little time today to update this with master, and made some changes based on the escalation checks PR I recently merged.

However, a couple of the unit tests still need to be updated (alertsms_test.go, for the changes to the message) before we can get this in.

The expected text will need to be updated with the new options, and part of the summary will need to be truncated a bit more (since it leaves less space for the rest of the text).

Let me know if you need help with this, you can run all the preflight checks with make check and just the unit tests with make test.

[Lakshmi2107]

@mastercactapus thanks a lot. I have modified the unit tests and pushed the changes. Please review.