proto/generic/cast.go: let Value struct func <Interface> support Enum…

[sbs-copilot]

A new optimization

What type of PR is this?

optimize: A new optimization

Check the PR title.

• This PR title match the format: (optional scope):
• The description of this PR title is user-oriented and clear enough for others to understand.
• Attach the PR updating the user documentation if the current PR requires user awareness at the usage level. User docs repo

(Optional) Translate the PR title into Chinese.

一个新的优化

(Optional) More detailed description for this PR(en: English/zh: Chinese).

en: This PR adds support for extracting the int value contained by an ENUM node.
zh(optional): 本PR新增了对提取ENUM节点并返回int32值的支持。

(Optional) Which issue(s) this PR fixes:

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(optional) The PR that updates user documentation:

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[AsterDY]

@sbs-copilot please sign CLA