[core] Modularize FileSource codebase (#15768)

* [core] Introduce FileSourceManager and use it for default platform impl

  - Add `FileSourceManager` interface that provides access to `FileSource`
    instances and means of registering / unregistering `FileSource` factories
  - Split `DefaultFileSource` into smaller parts
  - Add `DatabaseFileSource` interface and it's default implementation
  - Remove inter-dependencies between concrete `FileSource` classes

* [build] Add files to next build system

* [core] Add generic property setters / getters

* [core] Remove setOnlineStatus from OnlineFileSource interface

* [core] Hide threading implementation details from DatabaseFileSource interface

* [core] Make DB file source methods virtual

* [core] Add documentation for DatabaseFileSource and rename one method

* [core] Use simple callback instead of ActorRef

* [core] Remove ActorRef from OnlineFileSource public header

* [core] Add callback to FileSource::forward async API

* [core] Pass OfflineRegionDefinition by value

* [core] Update tests to use modular file sources

* [core] Update unit tests

* [core] Update unit tests after rebase

* [core] Backport low prio fix for cached requests

* [core] Backport pack database

* [core] Return removed factory from unRegisterFileSourceFactory

* [core] Rename shadowed args in onlinefilesource

* [core] Remove simple std::function callback aliases

* [core] Expose online file source property keys in public header file

* [test-runner] Add proxy file source test runner

* [cache] Update mbgl-cache utility to use new file source

* [metrics] Rebaseline binary size metrics

* [offline] Update offline utility

* [core] Update changelog

1 files changed, 10 insertions, 4 deletions

diff --git a/render-test/file_source.hpp b/render-test/file_source.hpp
index 34ba739a22..d0496ab8f6 100644
--- a/render-test/file_source.hpp
+++ b/render-test/file_source.hpp
@@ -1,15 +1,18 @@
 #pragma once
 
-#include <mbgl/storage/default_file_source.hpp>
+#include <mbgl/storage/file_source.hpp>
 
 namespace mbgl {
 
-class ProxyFileSource : public DefaultFileSource {
+class ResourceOptions;
+
+class ProxyFileSource : public FileSource {
 public:
-    ProxyFileSource(const std::string& cachePath, const std::string& assetPath);
+    ProxyFileSource(std::shared_ptr<FileSource>, const ResourceOptions&);
     ~ProxyFileSource();
 
-    std::unique_ptr<AsyncRequest> request(const Resource&, Callback);
+    std::unique_ptr<AsyncRequest> request(const Resource&, Callback) override;
+    bool canRequest(const Resource&) const override { return true; }
 
     /**
      * @brief Flag to change the networking mode of the file source.
@@ -39,6 +42,9 @@ public:
      * @return size_t
      */
     static size_t getTransferredSize();
+
+private:
+    std::shared_ptr<FileSource> defaultResourceLoader;
 };
 
 } // namespace mbgl