Add constant for 'Alt-Svc' to com.google.common.net.HttpHeaders

[sdavids]

API(s)

com.google.common.net.HttpHeaders

How do you want it to be improved?

Please add a constant for Alt-Svc.

Why do we need it to be improved?

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Alt-Svc

Example

response.setHeader(HttpHeaders.ALT_SVC, "h3-25=\":443\"; ma=3600, h2=\":443\"; ma=3600");

Current Behavior

no constant

Desired Behavior

constant for "Alt-Svc" exists

Concrete Use Cases

HTTP/3 endpoint advertisement in Java-based API gateway.

Checklist

• I agree to follow the code of conduct.

• I have read and understood the contribution guidelines.

• I have read and understood Guava's philosophy, and I strongly believe that this proposal aligns with it.

[kluever]

Fixed via 503ba42