feat: Add option to connect to a specific server

[cbaker6]

New Pull Request Checklist

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

Issue Description

The SDK currently doesn't allow the ability to connect to a different Parse Server than the one configured during initialization. This can make it hard to use the Swift SDK for Cloud Code in a multi-server environment.

Approach

Add the option to allow the developer to specify the URL for a specific call. If the URL string provided can't be turned into a real URL, default to the configured URL. This allows Swift Cloud Code to replicate directAccess by making all calls to the same server to complete a particular ParseHook or ParseTrigger.

TODOs before merging

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

[codecov]

Codecov Report

Merging #50 (7b81604) into main (c7c83f1) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main      #50   +/-   ##
=======================================
  Coverage   90.43%   90.44%           
=======================================
  Files         163      163           
  Lines       16482    16492   +10     
=======================================
+ Hits        14906    14916   +10     
  Misses       1576     1576           

Impacted Files	Coverage Δ
Sources/ParseSwift/API/API+Command.swift	89.90% <100.00%> (ø)
...urces/ParseSwift/API/API+NonParseBodyCommand.swift	82.14% <100.00%> (ø)
Sources/ParseSwift/API/API.swift	99.39% <100.00%> (+0.03%)	⬆️

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