fix(query): exclude null-ish values from query encoding

[ShuviSchwarze]

Closes: elysiajs/elysia#1094
Relevant: #129 #127

This PR explicitly exclude undefined and null properties from query string encoding due to URI query lack of support for sending null-ish values.

This lead to unintuitive behaviour on elysia, as well as t.Optional not working for the bellow case

const query = {
	username: "testUser",
	alias: undefined
}

const { data } = await client.query.get({
	query
})
// ?username=testUser&alias=undefined
// { username: "testUser", alias: "undefined" } 

From elysiajs/elysia#1094 (comment), this proposes null-ish values be excluded from query params following this recommendation

New behaviour

const query = { username: undefined }

const { data } = await client.query.get({
	query: { username: undefined }
})
// ?username=testUser
// { username: "testUser", alias: undefined } 

[fredericoo]

Suggested change

	const nonNullishQuery = query
	? Object.fromEntries(
	Object.entries(query).filter(
	([_, val]) => val !== undefined && val !== null
	)
	)
	: null
	const nonNullishQuery = query
	? Object.fromEntries(
	Object.entries(query).filter(
	([_, val]) => val != null)
	)
	)
	: null

js quirk: != null catches both undefined and null

[ShuviSchwarze]

Unless for performance reasons, I dont think relying on implicit behaviours is good