feat: support go expressions in script elements

[a-h]

Support the use of Go variables within <script> elements.

package testscriptexpressions

templ Script[T any](name string, data T) {
	<h1>{ name }</h1>
	<script>
		var a = {{ data }}
		var b = "{{ data }}"
		var c = '{{ data }}'
		var d = `{{ data }}`
	</script>
	<script>
		console.log({{ data }})
	</script>
}

templ AllTests() {
	@Script("string data", "hello")
	@Script("string data with quotes", "hello 'world'")
	@Script("numeric data", 123)
	@Script("boolean data", true)
	@Script("array data", []int{1, 2, 3})
	@Script("object data", struct {
		Name string
		Age  int
	}{"Alice", 30})
	@Script[*string]("null data", nil)
}

Result is:

<h1>string data</h1>
<script>
		var a = "hello"
		var b = "hello"
		var c = 'hello'
		var d = `hello`
</script>
<script>
		console.log("hello")
</script>
<h1>string data with quotes</h1>
<script>
		var a = "hello 'world'"
		var b = "hello \u0027world\u0027"
		var c = 'hello \u0027world\u0027'
		var d = `hello \u0027world\u0027`
</script>
<script>
		console.log("hello 'world'")
</script>
<h1>numeric data</h1>
<script>
		var a = 123
		var b = "123"
		var c = '123'
		var d = `123`
</script>
<script>
		console.log(123)
</script>
<h1>boolean data</h1>
<script>
		var a = true
		var b = "true"
		var c = 'true'
		var d = `true`
</script>
<script>
		console.log(true)
</script>
<h1>array data</h1>
<script>
		var a = [1,2,3]
		var b = "[1,2,3]"
		var c = '[1,2,3]'
		var d = `[1,2,3]`
</script>
<script>
		console.log([1,2,3])
</script>
<h1>object data</h1>
<script>
		var a = {"Name":"Alice","Age":30}
		var b = "{\u0022Name\u0022:\u0022Alice\u0022,\u0022Age\u0022:30}"
		var c = '{\u0022Name\u0022:\u0022Alice\u0022,\u0022Age\u0022:30}'
		var d = `{\u0022Name\u0022:\u0022Alice\u0022,\u0022Age\u0022:30}`
</script>
<script>
		console.log({"Name":"Alice","Age":30})
</script>
<h1>null data</h1>
<script>
		var a = null
		var b = "null"
		var c = 'null'
		var d = `null`
</script>
<script>
		console.log(null)
</script>

[a-h]

Needs an update to the documentation.

[joerdav]

This was confusing at first, but I understand now. This handles script components.

[joerdav]

Could be a parseFunc.

[a-h]

IIRC, function vars cause an allocation on init, hence a minor preference for not having them.

[a-h]

I think this is ready for review now. I ran the fuzz tests for a few hours, getting through about 73M tests without issue.