bugfix: socket + post with data

[AceCodePt]

Hi!

Found 2 problems:

1. making POST requests to pages with data (in any non empty format) doesn't return.
2. When using the @fastify/websocket, the vite websocket runs partially on fastify.

Fixed them.

However:
With these changes.,only the requests that were explicit towards fastify will be caught,
unlike the previous version where all was caught.

Upside:
I believe this is slightly faster then the previous algorithm, because we are dividing only for relevancy.

[AceCodePt]

@matthewp It doesn't support all the ways to encode information,
but it is a nice start.
Waiting on you mate :)

[tdnordine]

I need this fix for a project that I am working on, just to add an additional data-point. These changes work for my situation.

[AceCodePt]

I need this fix for a project that I am working on, just to add an additional data-point. These changes work for my situation.

for the mean while: @tdnordine
pnpm i AceCodePt/astro-fastify#bugfix/websocket-post-data