RFC-0005 Phase 2, annotated string functions and added tests.

[ScrapCodes]

Description

1. Annotated the scalar functions in StringFunctions class, with ScalarFunctionConstantStats and ScalarPropagateSourceStats .
2. Added appropriate tests to check if the stats propagation works as expected.
3. Updated AbstractCostBasedPlanTests to generate plans with this feature on and off.

Motivation and Context

https://github.com/prestodb/rfcs/blob/main/RFC-0005-functions-stats.md

Impact

None unless the user chooses to enable the feature via setting the session/feature flag.
A new session flag, scalar_function_stats_propagation_enabled and a new feature config will be introduced i.e. optimizer.scalar-function-stats-propagation-enabled, by setting this session flag or feature flag, this feature can be turned on or off.

When the feature is enabled, since string functions are annotated the effect of stats propagation can be measured or seen in the form of plan changes.

Test Plan

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• Please make sure your submission complies with our development, formatting, commit message, and attribution guidelines.
• PR description addresses the issue accurately and concisely. If the change is non-trivial, a GitHub Issue is referenced.
• Documented new properties (with its default value), SQL syntax, functions, or other functionality.
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• Adequate tests were added if applicable.
• CI passed.

Release Notes

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== NO RELEASE NOTE ==