fix: dynamic sized key-value pair

[ColinKYuen]

Summary

Fixes buffer Overflow for Large Connection String Key Values

Description

• Changes the allocation from stack to heap for parsing in values into the DataSource
• Also includes changes for allowing larger values to be read from the ODBC Data Source GUI
• Prior to changes, key-value pairs which contain values with length over 1024 will crash the application on a buffer overflow.

https://bugs.mysql.com/bug.php?id=119511

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[mysql-oca-bot]

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[ColinKYuen]

I confirm the code being submitted is offered under the terms of the OCA, and that I am authorized to contribute it.

[mysql-oca-bot]

Hi, thank you for your contribution. Your code has been assigned to an internal queue. Please follow
bug http://bugs.mysql.com/bug.php?id=119555 for updates.
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