feat: implemented link previews (proto files) (#3072)

* feat: implmented link previews (proto files)

* fix: passing proto linter errors

* chore: renamed MetadataService service in proto file.

* fix: removed unused files

* chore: removed meaningless comments from proto file

proto/gen/api/v2/link_service_grpc.pb.go

@@ -0,0 +1,109 @@
+// Code generated by protoc-gen-go-grpc. DO NOT EDIT.
+// versions:
+// - protoc-gen-go-grpc v1.3.0
+// - protoc             (unknown)
+// source: api/v2/link_service.proto
+
+package apiv2
+
+import (
+	context "context"
+	grpc "google.golang.org/grpc"
+	codes "google.golang.org/grpc/codes"
+	status "google.golang.org/grpc/status"
+)
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the grpc package it is being compiled against.
+// Requires gRPC-Go v1.32.0 or later.
+const _ = grpc.SupportPackageIsVersion7
+
+const (
+	LinkService_GetLinkMetadata_FullMethodName = "/memos.api.v2.LinkService/GetLinkMetadata"
+)
+
+// LinkServiceClient is the client API for LinkService service.
+//
+// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://pkg.go.dev/google.golang.org/grpc/?tab=doc#ClientConn.NewStream.
+type LinkServiceClient interface {
+	GetLinkMetadata(ctx context.Context, in *GetLinkMetadataRequest, opts ...grpc.CallOption) (*GetLinkMetadataResponse, error)
+}
+
+type linkServiceClient struct {
+	cc grpc.ClientConnInterface
+}
+
+func NewLinkServiceClient(cc grpc.ClientConnInterface) LinkServiceClient {
+	return &linkServiceClient{cc}
+}
+
+func (c *linkServiceClient) GetLinkMetadata(ctx context.Context, in *GetLinkMetadataRequest, opts ...grpc.CallOption) (*GetLinkMetadataResponse, error) {
+	out := new(GetLinkMetadataResponse)
+	err := c.cc.Invoke(ctx, LinkService_GetLinkMetadata_FullMethodName, in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// LinkServiceServer is the server API for LinkService service.
+// All implementations must embed UnimplementedLinkServiceServer
+// for forward compatibility
+type LinkServiceServer interface {
+	GetLinkMetadata(context.Context, *GetLinkMetadataRequest) (*GetLinkMetadataResponse, error)
+	mustEmbedUnimplementedLinkServiceServer()
+}
+
+// UnimplementedLinkServiceServer must be embedded to have forward compatible implementations.
+type UnimplementedLinkServiceServer struct {
+}
+
+func (UnimplementedLinkServiceServer) GetLinkMetadata(context.Context, *GetLinkMetadataRequest) (*GetLinkMetadataResponse, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method GetLinkMetadata not implemented")
+}
+func (UnimplementedLinkServiceServer) mustEmbedUnimplementedLinkServiceServer() {}
+
+// UnsafeLinkServiceServer may be embedded to opt out of forward compatibility for this service.
+// Use of this interface is not recommended, as added methods to LinkServiceServer will
+// result in compilation errors.
+type UnsafeLinkServiceServer interface {
+	mustEmbedUnimplementedLinkServiceServer()
+}
+
+func RegisterLinkServiceServer(s grpc.ServiceRegistrar, srv LinkServiceServer) {
+	s.RegisterService(&LinkService_ServiceDesc, srv)
+}
+
+func _LinkService_GetLinkMetadata_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(GetLinkMetadataRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(LinkServiceServer).GetLinkMetadata(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: LinkService_GetLinkMetadata_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(LinkServiceServer).GetLinkMetadata(ctx, req.(*GetLinkMetadataRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+// LinkService_ServiceDesc is the grpc.ServiceDesc for LinkService service.
+// It's only intended for direct use with grpc.RegisterService,
+// and not to be introspected or modified (even as a copy)
+var LinkService_ServiceDesc = grpc.ServiceDesc{
+	ServiceName: "memos.api.v2.LinkService",
+	HandlerType: (*LinkServiceServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "GetLinkMetadata",
+			Handler:    _LinkService_GetLinkMetadata_Handler,
+		},
+	},
+	Streams:  []grpc.StreamDesc{},
+	Metadata: "api/v2/link_service.proto",
+}