Add nonce support

[BillBuilt]

This adds support for nonces via templ.GetNonce(ctx)

[indaco]

Thanks for submitting this

I have one doubt.

While I can see the value of using GetNonce on script templates - https://templ.guide/security/content-security-policy/#nonces - it is unclear to me why on "style" tags.

I do not remember of CSS styles in goaster used to load or request resources or potentially execute client side code.

What's your opinion?

[smithcoin]

Allowing the nonce on all tags allows for a more restrictive CSP.