add axe.getRule(id)

[straker]

Need a public way to return an individual rule so we don't have to keep doing axe._audit.rules.find(ruleObj => ruleObj.id === ruleId)

[WilcoFiers]

Here's another use for this method: https://github.com/dequelabs/axe-core/pull/2648/files#diff-6cb05ef5f40343f1168c634a0aaa0c15f5e9cde40d7775c131ef70f263a7bc7aR34

[padmavemulapati]

devTask

[padmavemulapati]

Validated with the latest axe-core code base -
after run build, and latest axe.js built, run await axe.utils.getRule('region') , below is the details we can see:

also verified for few more rules:, bypass

for color-contrast

[padmavemulapati]

Tested on axe-expert_v4.6.0.03923, we can see the _audit details by running - utils.getRule('rule_id')