Feature/streamline backend requests (#297)

* Introduce "RequestManager"

* Use "RequestManager" - Simple replacements

 - Get rid of all "util/client" imports
 - replace old requests with new "RequestManager"
 - remove "fetcher" from global SWR config
     instead of using the SWR hooks by themselves, the "requestManager" is supposed to be used

* Use "RequestManager" - Do requests via SWR hooks

Use SWR hooks at places where it's easily usable

* Prevent trailing slashes in the "baseUrl"

src/components/MangaCard.tsx

@@ -19,6 +19,7 @@ import { GridLayout, useLibraryOptionsContext } from 'components/context/Library
 import { BACK } from 'util/useBackTo';
 import { IMangaCard } from 'typings';
 import { useTranslation } from 'react-i18next';
+import requestManager from 'lib/RequestManager';
 
 const BottomGradient = styled('div')({
     position: 'absolute',
@@ -87,8 +88,6 @@ const MangaCard = React.forwardRef<HTMLDivElement, IProps>((props: IProps, ref)
         options: { showUnreadBadge, showDownloadBadge },
     } = useLibraryOptionsContext();
 
-    const [serverAddress] = useLocalStorage<String>('serverBaseURL', '');
-    const [useCache] = useLocalStorage<boolean>('useCache', true);
     const [ItemWidth] = useLocalStorage<number>('ItemWidth', 300);
 
     const mangaLinkTo = { pathname: `/manga/${id}/`, state: { backLink: BACK } };
@@ -145,7 +144,7 @@ const MangaCard = React.forwardRef<HTMLDivElement, IProps>((props: IProps, ref)
                                 </BadgeContainer>
                                 <SpinnerImage
                                     alt={title}
-                                    src={`${serverAddress}${thumbnailUrl}?useCache=${useCache}`}
+                                    src={requestManager.getValidImgUrlFor(thumbnailUrl)}
                                     imgStyle={
                                         inLibraryIndicator && inLibrary
                                             ? {
@@ -232,7 +231,7 @@ const MangaCard = React.forwardRef<HTMLDivElement, IProps>((props: IProps, ref)
                                           imageRendering: 'pixelated',
                                       }
                             }
-                            src={`${serverAddress}${thumbnailUrl}?useCache=${useCache}`}
+                            src={requestManager.getValidImgUrlFor(thumbnailUrl)}
                         />
                         <Box
                             sx={{