* [base64] initial Base-64 re-implementation
* Add BufferView._assertBounds() functions
- they act the same as the _checkBounds() functions
- but only in debug mode
* Improve BufferView slicing
- when all the necessary checking has been done, the BufferView initializer doesn’t need to validate the buffer length another time.
* remove premature reference to typealias
* add the `unsafe` particle to an initializer argument label
* [base64] modify Base64 with `OutputBuffer` and `BufferView`
* remove unused bits in OutputBuffer
* express a cascaded if statement as a switch
* make internal decoding initializer failable
* Update Sources/FoundationEssentials/Data/Data+Base64.swift
Co-authored-by: Elliot Knight <63256761+Harry-KNIGHT@users.noreply.github.com>
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Co-authored-by: Elliot Knight <63256761+Harry-KNIGHT@users.noreply.github.com>
