Rename Sms{Service,Receiver} to WebOTPService

The old name does not reflect the changes made to the feature name
and specification. No change in functionality is expected.


The following changes were made using grep & sed.

- rename files
- [^_]+sms_service->webotp_service
- [^_]+sms_receiver->webotp_service
- {SMS,Sms}Receiver->WebOTPService
- SmsService->WebOTPService
- SMS Service->WebOTP Service

The only manual change were:
 - update some outdated documentation in webotp_service.mojom
 - SMSReceiver -> WebOTP for flags


## Aside
Getting a pre-submit warning which seems incorrect as we have not
changes the UMA histogram name and it exists :-?

```
** Presubmit Warnings **
Some UMA_HISTOGRAM lines have been modified and the associated histogram name has no match in either tools/metrics/histograms/histograms.xml or the modifications of it:
   [components/browser_ui/sms/android/java/src/org/chromium/components/browser_ui/sms/WebOTPServiceUma.java:35] Blink.Sms.Receive.TimeCancelOnKeyboardDismissal
```

Bug:1117238

Change-Id: I369f8631450b0a539b3c2afbf8d4ed87ce853a87
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2424707
Commit-Queue: Majid Valipour <[email protected]>
Reviewed-by: Alexei Svitkine <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Reviewed-by: Kentaro Hara <[email protected]>
Reviewed-by: Sam Goto <[email protected]>
Reviewed-by: Yi Gu <[email protected]>
Cr-Commit-Position: refs/heads/master@{#816889}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 9d0ba177..be6a9035 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -1241,8 +1241,8 @@
 extern const char kSmoothScrollingName[];
 extern const char kSmoothScrollingDescription[];
 
-extern const char kSmsReceiverCrossDeviceName[];
-extern const char kSmsReceiverCrossDeviceDescription[];
+extern const char kWebOTPCrossDeviceName[];
+extern const char kWebOTPCrossDeviceDescription[];
 
 extern const char kSpeculativeServiceWorkerStartOnQueryInputName[];
 extern const char kSpeculativeServiceWorkerStartOnQueryInputDescription[];