[FIX] Prevent CustomEmoji image URL double url escaping

[jungeonkim]

@RocketChat/ios

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Codecov Report

❗ No coverage uploaded for pull request base (develop@32e5363). Click here to learn what that means.
The diff coverage is 100%.

@@            Coverage Diff             @@
##             develop    #2679   +/-   ##
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  Coverage           ?   25.71%           
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  Files              ?      467           
  Lines              ?    17531           
  Branches           ?        0           
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  Hits               ?     4508           
  Misses             ?    13023           
  Partials           ?        0

Impacted Files	Coverage Δ
Rocket.Chat/Models/CustomEmoji.swift	88.88% <100%> (ø)

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[rafaelks]

@jungeonkim Are you seeing any problem that this change will fix it?

[jungeonkim]

@rafaelks Yes. I tested it to work.
This problem is not a problem with custom emoji with names in common ASCII ranges, but custom emoji with URL escaped names like Korean(for example "웃음") does not currently shown properly.

[rafaelks]

@jungeonkim Thank you! :-)