[4.x] Antlers: Allow number literals inside variable bindings

[JohnathonKoster]

This PR removes an existing papercut by allowing number literals inside Antlers parameter variable bindings. Currently, it is difficult/non-obvious on how one should go about passing a numeric value to a tag, as normal parameters are converted to strings:

{{ my_tag param="1234" }}

We can now simply use variable binding syntax to pass along the numeric literal:

{{ my_tag :param="1234" }}
{{ my_tag :param="-1234" }}
{{ my_tag :param="1234.56" }}

The current behavior would treat the numeric literal as a variable name, which is invalid, and always end up returning null, so I don't see this is as a breaking change. This PR does not automatically cast numeric values in all other situations since that would be a breaking change:

The following will remain a string value:

{{ my_tag param="1234" }}

The behavior of the following has not been changed, as it is possible for tags to start with numbers:

{{ my_tag param="{404}" }}

[aerni]

I believe this is a breaking change.

I've got this Antlers code:

{{ partial:components/section_header
    :eyebrow="block:header:eyebrow"
    :title="block:header:title"
    :text="block:header:text"
}}

Before this update, the dump inside this partial looked like this:

After this update, the dump looks like this:

This is the header data:

[aerni]

Using the {} syntax instead of : works:

[aerni]

@JohnathonKoster tracked it down to be related to PR #9499 and not this PR at all. Fix is incoming. Thanks!