refactor: Switch mounting point for Playgrounds

[cbaker6]

New Pull Request Checklist

• I am not disclosing a vulnerability.
• I am creating this PR in reference to an issue.

Issue Description

The mounting point for playgrounds works more consistently when it's a String instead of an Int.

Approach

• Change the Playground mount from /1 to /parse
• Sometimes a ParseFile doesn't sent url. Make decoding url optional
• Decode the functionName and triggerName when receiving Parse Hook requests.

TODOs before merging

• Add tests
• Add entry to changelog
• Add changes to documentation (guides, repository pages, in-code descriptions)

[codecov]

Codecov Report

Merging #52 (2f579f3) into main (cbfed65) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #52      +/-   ##
==========================================
+ Coverage   90.41%   90.44%   +0.02%     
==========================================
  Files         163      163              
  Lines       16492    16492              
==========================================
+ Hits        14912    14916       +4     
+ Misses       1580     1576       -4     

Impacted Files	Coverage Δ
...es/ParseSwift/Types/ParseHookFunctionRequest.swift	100.00% <ø> (ø)
...ces/ParseSwift/Types/ParseHookTriggerRequest.swift	100.00% <ø> (ø)
Sources/ParseSwift/Types/ParseFile.swift	95.45% <100.00%> (ø)
Sources/ParseSwift/Objects/ParseObject+async.swift	96.29% <0.00%> (-0.38%)	⬇️
Sources/ParseSwift/Coding/ParseEncoder.swift	78.14% <0.00%> (+0.11%)	⬆️
Sources/ParseSwift/LiveQuery/ParseLiveQuery.swift	75.11% <0.00%> (+0.58%)	⬆️

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