Fix forEach issue for eh-bookmark

[TaYaKi71751]

Related Issue

• Some galleries cannot get EHash by ?next=${id + 1} #282

• Add duckduckgo for ehash
• Use duckduckgo search with proxied request
• Add cache for ehash

• https://stackoverflow.com/questions/42467663/how-to-async-await-in-list-foreach-in-dart

• Fix forEach issue for eh-bookmark
• Use loading
• Use same index with loading

[TaYaKi71751]

I tested on Android

• when use articleList.forEach((element) async {})

• Bookmark wasn't loaded

• when use await Future.forEach(articleList,(element) async {})

• Bookmark was loaded

[TaYaKi71751]

BUT

Use loading
was worked too

[TaYaKi71751]

some gallery_token could not be search by ?next=${(id) + 1}
then just add use duckduckgo when could not be search by ?next=${(id) + 1}

[TaYaKi71751]

I need to add proxied duckduckgo search

[TaYaKi71751]

Just can watch tags on bookmark page
(Tested on LM-G710N)

[TaYaKi71751]

moved to #292
with TaYaKi71751#8 (merge to upstream)