🪲 Highlight pressed keyword when expected key is a number key

[brianpeiris]

Fixes #5757

The highlighting grammar for Level 13 explicitly allowed for Numbers when using the pressed keyword, as part of the EqualityCheck rule. Subsequent grammars (Level 14-18) omitted Numbers since the rule was split out into a dedicated PressedCheck rule. This PR reintroduces Numbers in the pressed grammar rule to fix the highlighting when expecting a number key press.

How to test

Follow these steps to verify this PR works as intended:

• Visit http://localhost:8080/hedy/14#debugging
• Paste in the following code:

if 1 is pressed
    print 'one'
else
    print 'waiting for second key'
    if x is pressed
        print 'x'
    else
        print '?'

• See that pressed is highlighted orange in both if conditions
• Visit http://localhost:8080/hedy/17#debugging
• Paste in the following code:

stop = False
key = 'x'
while stop == False:
    if 1 is pressed:
        print 'one'
    elif a is pressed:
        print 'a'
    elif key is pressed:
        print 'x'
        stop = True
    else:
        print '?'

• See that pressed is highlighted orange in all the if and elif conditions

Checklist

• [x] Contains one of the PR categories in the name
• [x] Describes changes in the format above
• [x] Links to an existing issue or discussion
• [x] Has a "How to test" section

[Felienne]

Thanks for the fix @brianpeiris!

We are about to make some large changes to the grammar (see https://github.com/hedyorg/hedy/pull/6329) which will then also impact the highlighter, so we need to keep this PR for a little while until @jpelay is ready with the highlighter.

@jpelay Can you take this into account when updating the highlighter?