JSON package

[panhania]

This is heavily inspired by #38 but fixes several issues we had with using that package:

• sometimes incorrect invocations return NULL and sometimes they fail with an exception, for example SELECT JSON_EXTRACT_PATH_TEXT('{ "123": 123 }', '123.23'); exits abnormally while SELECT JSON_EXTRACT_PATH_TEXT('{ "foo": "bar" }', 'baz'); yields NULL
• no support for array indexing
• no support or well-defined behavior for weird cases like keys with dots or empty strings
• performance issues (parsing string to an AST just to serialize it to JSON string again, many unnecessary heap allocations)

Our package, hopefully, solves all these and runs in constant memory doing no heap allocations. Refer to the README file and usage samples for more information.

The only caveat is very liberal custom JSON parser that often works with malformed JSONs (which may or may not be something you want).

[CLAassistant]

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