avoid duplicate generate sql digest & normalized sql for prepared stmt

[lysu]

Feature Request

Is your feature request related to a problem? Please describe:

generate digest or normalize has some performance cost

when SQL executed as prepared statement, normalize sql and sql digest should be prepare once and reuse forever

Describe the feature you'd like:

RT

Describe alternatives you've considered:

n/a

Teachability, Documentation, Adoption, Migration Strategy:

n/a

[TszKitLo40]

Can I try this issue? But I may need more advice from you to fix it. @lysu