Add useful template functions to jq filters

[heaths]

Relates to #10262 but needs to be used in cli/cli if accepted.

[0xdevalias]

if acceptable to the CLI devs, this could be the basis for using some --template functions in --jq filters

If acceptable, I can document this in the CLI's README and help content

@heaths Sounds good to me! Appreciate your efforts! 🖤

[0xdevalias]

Relates to #10262 but needs to be used in cli/cli if accepted.

Proper link to issue (since it's in a different repo):

• https://github.com/cli/cli/issues/10262

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@andyfeller Curious if you (or someone more appropriate on your team perhaps) had some bandwidth to give a /2c on this PR in general; particularly around if/what concerns/blockers there would be to landing it (aside from the obvious fact that it needs a rebase; but if there are larger concerns with the feature/approach then that sort of 'polish'/'upkeep' would be irrelevant)

I know there is this issue for some of the more tangentially related issues connected to this; but looking at the changes here, I don't think this PR would really fall under the scope of the concerns raised in it:

• https://github.com/cli/cli/issues/10558