chore: move Installation and Push to platform's domain folders (#5085)

* chore: set up a `CODEOWNERS` space for platform

* chore: move sql objects for `Installation` to platform's domain

* chore: move `Installation` and `PushRelay` code to platform's domain

src/Infrastructure.Dapper/Platform/Installations/Repositories/InstallationRepository.cs

@@ -0,0 +1,26 @@
+using Bit.Core.Platform.Installations;
+using Bit.Core.Settings;
+using Bit.Infrastructure.Dapper.Repositories;
+
+#nullable enable
+
+namespace Bit.Infrastructure.Dapper.Platform;
+
+/// <summary>
+/// The CRUD repository for communicating with `dbo.Installation`.
+/// </summary>
+/// <remarks>
+/// If referencing: you probably want the interface `IInstallationRepository`
+/// instead of directly calling this class.
+/// </remarks>
+/// <seealso cref="IInstallationRepository"/>
+public class InstallationRepository : Repository<Installation, Guid>, IInstallationRepository
+{
+    public InstallationRepository(GlobalSettings globalSettings)
+        : this(globalSettings.SqlServer.ConnectionString, globalSettings.SqlServer.ReadOnlyConnectionString)
+    { }
+
+    public InstallationRepository(string connectionString, string readOnlyConnectionString)
+        : base(connectionString, readOnlyConnectionString)
+    { }
+}