patcher: refactor (#808)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change
Refactor patch manager.

This one file had the UI logic, config save/load, parsing patches JSON,
applying memory patches, everything all in one cpp file. Refactor and
separate out the layers.

## Testing
Sanity checked patch workflows.

src/spice2x/patcher/internal.h

@@ -0,0 +1,57 @@
+#pragma once
+
+#include "patch_manager.h"
+#include "external/rapidjson/document.h"
+#include "util/nt_loader.h"
+
+namespace patcher {
+
+    // internal engine state (patcher module only)
+    extern std::vector<std::string> setting_auto_apply_list;
+    extern std::vector<std::string> setting_patches_enabled;
+    extern std::map<std::string, std::string> setting_union_patches_enabled;
+    extern std::map<std::string, int64_t> setting_int_patches_enabled;
+    extern std::filesystem::path LOCAL_PATCHES_PATH;
+    extern std::map<std::string, std::vector<std::string>> EXTRA_DLLS;
+    extern bool ldr_registered;
+    extern void *ldr_notify_cookie;
+    extern std::vector<std::string> ldr_target_libraries;
+
+    // internal helpers
+    void append_patches(
+        std::string& patches_json,
+        bool apply_patches = false,
+        std::function<bool(const PatchData&)> filter = std::function<bool(const PatchData&)>(),
+        std::string pe_identifier_for_patch = "");
+    bool is_game_id_wildcard_matched(const std::string& id_from_config);
+    std::string getFromUrl(const std::string& dll_name, const std::string& url);
+    bool load_from_patches_json(bool apply_patches);
+    void load_embedded_patches(bool apply_patches);
+    bool import_remote_patches_for_dll(const std::string& url, const std::string& dll_name);
+    VOID CALLBACK loader_notification(ULONG reason, PCLDR_DLL_NOTIFICATION_DATA data, PVOID context);
+
+    std::string patch_hash(PatchData& patch);
+    void clear_dll_maps();
+
+    int64_t parse_little_endian_int(uint8_t *bytes, size_t size);
+    void int_to_little_endian_bytes(int64_t value, uint8_t *bytes, size_t size);
+
+    std::vector<uint8_t> *find_in_dll_map(
+        const std::string& dll_name, size_t offset, size_t size);
+    std::vector<uint8_t> *find_in_dll_map_org(
+        const std::string& dll_name, size_t offset, size_t size);
+
+    bool restore_bytes_from_dll_map_org(
+        uint8_t *destination, const std::string& dll_name, size_t offset, size_t size);
+
+    void create_dll_backup(
+        std::vector<std::filesystem::path>& written_list, const std::filesystem::path& dll_path);
+    std::string fix_up_dll_name(const std::string& dll_name);
+    uint8_t *get_dll_offset_for_patch_apply(
+        const std::string& dll_name, uint64_t data_offset, size_t size_in_bytes);
+
+    uint64_t parse_json_data_offset(
+        const std::string& patch_name, const rapidjson::Value& value);
+
+    void print_auto_apply_status(PatchData& patch);
+}