Update Base64 as a non-throwing API

[Joe-Abraham]

Follow-up PR: #10371

The following changes are done in this PR.

1. Variable names are updated for better readability.
2. Function declarations in Base64.h for better maintainability.
3. Refactor the APIs in Base64 as non-throwing APIs.

Changing the char to std::string_view and std::string will be done in subsequent PR.

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[Joe-Abraham]

@majetideepak Can you please review the changes?

[kgpai]

Thanks @Joe-Abraham , based on brief glance, it seems its mostly renaming variables etc for readability and consistency (which is welcome change); Want to make sure I am not missing any material change.

[Joe-Abraham]

@kgpai I have also made the APIs used in BinaryFunctions.h as non-throwing.

[majetideepak]

3. Refactor the APIs in Base64 as non-throwing APIs.

@Joe-Abraham this should be its own PR since its a functional change. We can leave the remaining code improvements this PR.
Can you please open another PR with only the non-throwing API changes? Thanks.