Remove Cocoapods support

[AvdLee]

Swift Package Manager is the future and it turned out to no longer be easy to maintain CocoaPods support. It's not really worth the effort anymore.

Part of the reason are these kind of errors:

[09:35:20]: Pod push failed: Exit status of command 'pod trunk push' was 1 instead of 0.
[!] Found podspec `Diagnostics.podspec`
Adding spec repo `trunk` with CDN `https://cdn.cocoapods.org/`
Updating spec repo `trunk`
Validating podspec
 -> Diagnostics
 -> Diagnostics (2.0.0)
    - ERROR | [iOS] xcodebuild: Returned an unsuccessful exit code. You can use `--verbose` for more information.
    - NOTE  | xcodebuild:  note: Using new build system
    - NOTE  | xcodebuild:  note: Using codesigning identity override: -
    - NOTE  | xcodebuild:  note: Build preparation complete
    - NOTE  | [iOS] xcodebuild:  note: Planning
    - NOTE  | [iOS] xcodebuild:  note: Building targets in parallel
    - NOTE  | [iOS] xcodebuild:  warning: Capabilities for Signing & Capabilities may not function correctly because its entitlements use a placeholder team ID. To resolve this, select a development team in the App editor. (in target 'App' from project 'App')
    - ERROR | xcodebuild:  Diagnostics/Sources/DiagnosticsReporter.swift:105:35: error: type 'Bundle' has no member 'module'
    - ERROR | xcodebuild:  Diagnostics/Sources/DiagnosticsReporter.swift:105:87: error: 'nil' requires a contextual type
    - ERROR | xcodebuild:  Diagnostics/Sources/DiagnosticsReporter.swift:112:39: error: type 'Bundle' has no member 'module'
    - ERROR | xcodebuild:  Diagnostics/Sources/DiagnosticsReporter.swift:112:94: error: 'nil' requires a contextual type

In which the Bundle.module is not available through CocoaPods. On top of that; our latest releases weren't even released through CocoaPods and we didn't get any complain.

Users will be able to either add the SPM package manually or automatically, which should be good enough.

[wetransferplatform]

	Messages
📖	View more details on Bitrise
📖	DiagnosticsTests: Executed 18 tests, with 0 failures in 0.255 seconds

Code Coverage Report

Name	Coverage
Diagnostics	71.39%	⚠️

Generated by 🚫 Danger Swift against ab13bb5

[wetransferplatform]

Congratulations! 🎉 This was released as part of Release 2.1.0 🚀

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[alexiscreuzot]

Worst idea ever to remove support for Cocoapods...