feat: change to singleton instance for TdsParser.cs and TdsParserStat…

[javiermendozain]

Change to singleton instance for TdsParser.cs and TdsParserStateObjectManaged.cs, TdsParserStateObjectNative.cs to reduce memory leaks for those objects.

Evidence:

Before the changes, each execution generated instances of TdsParser and TdsParserStateObjectManaged, which remained unused in memory, leading to a memory leak.
Before changes

This memory leak was observed in services deployed on k8s with Linux pods.
Memory leak

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After the changes, each execution reused the objects TdsParser and TdsParserStateObjectManaged.
After changes

[javiermendozain]

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[javiermendozain]

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[vonzshik]

I'm probably missing something, but every time this method is called it's going to return a new instance of TdsParser.

[Wraith2]

I don't understand how this change would help. All it does is move the new into a helper function.

Have you been able to track down the retention root for the instances that you see increasing? This is purely managed code so you're probably not really seeing a leak you're seeing unexpected retention.