refactor: convert imapmessage class from java to kotlin

package com.fsck.k9.mail.store.imap;

package com.fsck.k9.mail.store.imap

import com.fsck.k9.mail.internet.MimeMessage

import com.fsck.k9.mail.internet.MimeMessage;

class ImapMessage(uid: String) : MimeMessage() {

    init {

        this.mUid = uid

public class ImapMessage extends MimeMessage {

    ImapMessage(String uid) {

        this.mUid = uid;

    }

    }

    public void setSize(int size) {

    fun setSize(size: Int) {

        this.mSize = size;

        this.mSize = size

    }

    }

}

}