Strip some uses of @JvmStatic from runtime

[cbrunsdon]

I'm vaguely confident none of these @JvmStatic usages are required and can all be safely removed.

I'm not exactly swimming in kotlin or KMP experience but getting a handle on the internal.@Jvm* usages from various PR's and issues like this one led me down a few rabbit holes so figured I'd send the PR while I was poking around and getting an understanding of its purpose/usage.

Disclaimers:

• Got as many gradle tasks/test to run/build as I could before running into various things that wanted me to have an android SDK,, but haven't ran a full ./gradle build
• I hope this fits under the "small contributions" clause of the "we don't want commits" from the website
• Signed the contributor agreement

[cbrunsdon]

The API compatability tests are failing with

-	public static final fun get$wire_runtime (I)Lcom/squareup/wire/FieldEncoding;

I'm surprised that shows up in the api diff, attempting to access it from Java I get what I expected:

Cannot access 'fun get(value: Int): FieldEncoding': it is internal in 'com.squareup.wire.FieldEncoding.Companion'.

I can either add back the @JvmStatic or take it out of the .api, whichever you prefer. It wasn't marked with the internal.@JvmStatic which started my rabbit-holing.

Or, seeing as it is both unused and internal, I can remove the companion/operator entirely and remove it from the API