Alerting: Support tls config for webhook receiver (#93513)

Adds the ability to configure tls settings on the webhook receiver (e.g. to skip server certificate validation)

docs/sources/administration/provisioning/index.md

@@ -614,12 +614,22 @@ The following sections detail the supported settings and secure settings for eac
 
 #### Alert notification `webhook`
 
-| Name       | Secure setting |
-| ---------- | -------------- |
-| url        |                |
-| httpMethod |                |
-| username   |                |
-| password   | yes            |
+| Name        | Secure setting |
+| ----------- | -------------- |
+| url         |                |
+| http_method |                |
+| username    |                |
+| password    | yes            |
+| tls_config  |                |
+
+##### TLS config
+
+| Name               | Secure setting |
+| ------------------ | -------------- |
+| insecureSkipVerify |                |
+| clientCertificate  | yes            |
+| clientKey          | yes            |
+| caCertificate      | yes            |
 
 #### Alert notification `googlechat`
 

docs/sources/alerting/set-up/provision-alerting-resources/file-provisioning/index.md

@@ -616,6 +616,16 @@ settings:
   authorization_credentials: abc123
   # <string>
   maxAlerts: '10'
+  # <map>
+  tlsConfig:
+    # <bool>
+    insecureSkipVerify: false
+    # <string>
+    clientCertificate: certificate in PEM format
+    # <string>
+    clientKey: key in PEM format
+    # <string>
+    caCertificate: CA certificate in PEM format
 ```
 
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