Remove field name decapitalization in the scheme

[pleshakov]

Proposed changes

Problem:

For consistency with DataFabric examples, we make field names start with lowercase letter. As a result, we convert the first character of field name in a go struct to lowercase. For example, MyField -> myField. However, the generated scheme names for fields like HTTPRoutes look a bit ugly: HTTPRoutes -> hTTPRoutes

Solution:

Because it is not a hard requirement for Avro scheme, we can use names like HTTPRoutes just fine.

long? HTTPRoutes = null;

CLOSES -- #33

Note:
The alternative here is to support go tags like

HTTPRoutes int64 `avro:"httpRoutes"

So that in the generated scheme, it will be:

long? httpRoutes = null;

However, that would lead to +173 lines of code (I originally went with that approach)

Checklist

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• I have read the CONTRIBUTING
  guide
• I have proven my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have ensured the README is up to date
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch on my own fork