Compute enum hashes at compile time

[SergeyRyabinin]

Issue #, if available:
HashString is called 254 times when S3 shared object is loaded at the static init stage
Description of changes:
Use constexpr to calculate this values at the build time.
HashString will be called only 28 times when loading a core+s3 libs.
Check all that applies:

• Did a review by yourself.
• Added proper tests to cover this PR. (If tests are not applicable, explain.)
• Checked if this PR is a breaking (APIs have been changed) change.
• Checked if this PR will not introduce cross-platform inconsistent behavior.
• Checked if this PR would require a ReadMe/Wiki update.

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