Add constructors

[MasayukiSuda]

add constructors

    public Mp4Composer(@NonNull final String srcPath, @NonNull final String destPath) {
        this.srcDataSource = new FilePathDataSource(srcPath, logger, errorDataSource);
        this.destPath = destPath;
    }

    public Mp4Composer(@NonNull final FileDescriptor srcFileDescriptor, @NonNull final String destPath) {
        this.srcDataSource = new FileDescriptorDataSource(srcFileDescriptor);
        this.destPath = destPath;
    }

    public Mp4Composer(@NonNull final Uri srcUri, @NonNull final String destPath, @NonNull final Context context) {
        this.srcDataSource = new UriDataSource(srcUri, context, logger, errorDataSource);
        this.destPath = destPath;
    }

    @TargetApi(Build.VERSION_CODES.O)
    public Mp4Composer(@NonNull final FileDescriptor srcFileDescriptor, @NonNull final FileDescriptor destFileDescriptor) {
        if (Build.VERSION.SDK_INT < 26) {
            throw new IllegalArgumentException("destFileDescriptor can not use");
        }
        this.srcDataSource = new FileDescriptorDataSource(srcFileDescriptor);
        this.destPath = null;
        this.destFileDescriptor = destFileDescriptor;
    }

    @TargetApi(Build.VERSION_CODES.O)
    public Mp4Composer(@NonNull final Uri srcUri, @NonNull final FileDescriptor destFileDescriptor, @NonNull final Context context) {
        if (Build.VERSION.SDK_INT < 26) {
            throw new IllegalArgumentException("destFileDescriptor can not use");
        }
        this.srcDataSource = new UriDataSource(srcUri, context, logger, errorDataSource);
        this.destPath = null;
        this.destFileDescriptor = destFileDescriptor;
    }

related issues

#48