Add tests for different Postgres client libraries (#2008)

* Add tests for different postgres clients
* test/fixtures: sanitize test name for test_output_dir
* test/fixtures: do not look for etcd before runtime
* Add workflow for testing Postgres client libraries

test_runner/pg_clients/swift/PostgresClientKitExample/Sources/PostgresClientKitExample/main.swift

@@ -0,0 +1,38 @@
+import Foundation
+
+import PostgresClientKit
+
+do {
+    var configuration = PostgresClientKit.ConnectionConfiguration()
+
+    let env = ProcessInfo.processInfo.environment
+    if let host = env["NEON_HOST"] {
+        configuration.host = host
+    }
+    if let database = env["NEON_DATABASE"] {
+        configuration.database = database
+    }
+    if let user = env["NEON_USER"] {
+        configuration.user = user
+    }
+    if let password = env["NEON_PASSWORD"] {
+        configuration.credential = .scramSHA256(password: password)
+    }
+
+    let connection = try PostgresClientKit.Connection(configuration: configuration)
+    defer { connection.close() }
+
+    let text = "SELECT 1;"
+    let statement = try connection.prepareStatement(text: text)
+    defer { statement.close() }
+
+    let cursor = try statement.execute(parameterValues: [ ])
+    defer { cursor.close() }
+
+    for row in cursor {
+        let columns = try row.get().columns
+        print(columns[0])
+    }
+} catch {
+    print(error)
+}