Fixes #2079: Update "From Base32" operation to support strict mode and custom padding

[irebased]

Description

This implements #2079

The From Base64 operation allows for a strict mode, and also allows removing the padding character from the alphabet. The From Base32 operation, on the other hand, is not aligned with this design and produces an "Invalid byte array".

This change updates the Base32 operation to include a strict mode, which enforces the same rules as the Base64 tool (adhering to Base32 expectations instead of Base64, such as a maximum of 6 padding characters). In non-strict mode, this allows the user to enter inputs that are not divisible by 8 while still producing a valid output, even without a padding character.

This change also enables users to provide custom padding characters instead of forcing =.

Example:

• Input: "GE"
• Alphabet: "A-Z2-7"

Existing result:

Result after this change:

How it works

• Updates the default encoded character to be null instead of = to allow for the absence of a padding character
• Updates the Base32 logic to allow for a custom padding character instead of hard-coding =
• Only pushes a character to the byte array if it is between 0 and 256 to avoid pushing -1 and causing an invalid byte array
• Strict mode forces the text to not be 5n + 1 in length as it is an invalid length for a Base32 string.

Testing

All unit tests for Base32 continue to pass after this change. I also tested the following inputs and got valid results:

• "GE" with alphabet "A-Z2-7" produces output "1"
• "JBSWY3DP" with alphabet "A-Z2-7" produces "Hello"
• "O4" with alphabet "A-Z2-7" produces "04"
• "04=======" produces error "Error: Invalid Base32 input length (9). Cannot be 8n+1, even without padding chars."
• "..." produces error "Error: Base32 input contains non-alphabet char(s)"

References

See the Base64 implementation.

[CLAassistant]

All committers have signed the CLA.