CI(pg-clients): unify workflow with build-and-test (#8160)

## Problem

`pg-clients` workflow looks different from the main `build-and-test`
workflow for historical reasons (it was my very first task at Neon, and 
back then I wasn't really familiar with the rest of the CI pipelines).
This PR unifies `pg-clients` workflow with `build-and-test`

## Summary of changes
- Rename `pg_clients.yml` to `pg-clients.yml`
- Run the workflow on changes in relevant files
- Create Allure report for tests
- Send slack notifications to `#on-call-qa-staging-stream` channel
(instead of `#on-call-staging-stream`)
- Update Client libraries once we're here

test_runner/pg_clients/swift/PostgresClientKitExample/Dockerfile

@@ -1,11 +1,11 @@
-FROM swift:5.9 AS build
+FROM swift:5.10 AS build
 RUN apt-get -q update && apt-get -q install -y libssl-dev
 WORKDIR /source
 
 COPY . .
 RUN swift build --configuration release
 
-FROM swift:5.9
+FROM swift:5.10
 WORKDIR /app
 COPY --from=build /source/.build/release .
 CMD ["/app/PostgresClientKitExample"]

test_runner/pg_clients/swift/PostgresClientKitExample/Package.resolved

@@ -1,4 +1,5 @@
 {
+  "originHash" : "8eff8c577ba246ce7824d3434839acefced2b1a1d2b1ad700554502538a50558",
   "pins" : [
     {
       "identity" : "bluesocket",
@@ -18,15 +19,6 @@
         "version" : "2.0.2"
       }
     },
-    {
-      "identity" : "openssl",
-      "kind" : "remoteSourceControl",
-      "location" : "https://github.com/Kitura/OpenSSL.git",
-      "state" : {
-        "revision" : "5dc8cb4f971135c17343e3c6df4f28904a0600e2",
-        "version" : "2.3.1"
-      }
-    },
     {
       "identity" : "postgresclientkit",
       "kind" : "remoteSourceControl",
@@ -37,5 +29,5 @@
       }
     }
   ],
-  "version" : 2
+  "version" : 3
 }

test_runner/pg_clients/swift/PostgresClientKitExample/Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.8
+// swift-tools-version:5.10
 import PackageDescription
 
 let package = Package(