Add Po18csParser

[Yomafil]

Add new parser for site https://www.po18cs.com #1644

We get the missing chapter links from the next chapter button present in the previous chapter.
Short book: https://www.po18cs.com/book/126352/

Also added a new function in ChapterUrlsUI monoShowTocProgress to show the ToC Progress for individual chapter instead of multiple at once, as we are only getting one chapter at a time and showTocProgress only takes in a list of chapters.
Useful to track the progress for large books: https://www.po18cs.com/book/6/

[Yomafil]

It should also be possible to pass the chapter as an array of 1 into showTocProgress instead of using the new monoShowTocProgress if we don't want to make a new function.

async getChapterUrls(dom, chapterUrlsUI) {
        let menu = [...dom.querySelectorAll("dd.col-md-3")];

        let chapters = [];
        let prevChapUrl = null;

        for (let el of menu) {
            let anchor = el.querySelector("a");

            let chapter = null;

            if (anchor) {
                prevChapUrl = anchor.href;

                chapter = {
                    sourceUrl: anchor.href,
                    title: el.textContent.trim(),
                    isIncludeable: true,
                };

                chapters.push(chapter);

                chapter = [chapter];

                chapterUrlsUI.showTocProgress(chapter);

                continue;
            }

            //Handle missing chapter link in toc
            await this.rateLimitDelay();
            let options = { parser: this };
            let prevChapDom = (await HttpClient.wrapFetch(prevChapUrl, options)).responseXML; 

            let nextChapAnchor = prevChapDom.querySelector("#linkNext");

            prevChapUrl = nextChapAnchor.href;

            chapter = {
                sourceUrl: nextChapAnchor.href,
                title: el.textContent.trim(),
                isIncludeable: true,
            };

            chapters.push(chapter);

            chapter = [chapter];
            
            chapterUrlsUI.showTocProgress(chapter);
        }

        return chapters;
    }
    ```

[gamebeaker]

@Yomafil i removed monoShowTocProgress as the change to call the original is a simple [] wrap.