Fix vault path-help for selected paths with bad regexps

[maxb]

Describe the bug
When a Vault API path has been defined with a regex that requires a final slash, the vault path-help command is unable to retrieve help for it.

Underlying cause
Vault's code automatically appends a trailing slash on to all paths used for ListOperations, but removes a trailing slash for all other operations, including HelpOperations. In order for a path pattern to match both ListOperation and HelpOperation, it must accept both the presence and absence of a trailing slash.

To Reproduce, or test the fix

1. Start a Vault dev server
2. Run vault path-help auth/token/accessors/
3. See an unsupported path error

Expected behavior
Help message displayed as expected.

Fix
Update the few path regex patterns that fall into this trap to end with /? instead of /.

Update a comment to explain why.

[maxb]

Hi @hsimon-hashicorp @miagilepner,

Apologies for the direct @-ing - I wasn't sure if there was any better contact method, so I just picked some people I have seen triage community submissions in the past.

I have quite a few open Vault PRs that have been sitting around for a while, so I picked this one - one of my smaller, hopefully easier to review ones - in which to ask: Is there anything I can do to make these easier for HashiCorp engineers to review and merge?

[hghaf099]

@maxb I will be reviewing this PR. Thanks for putting it together. It looks great from the first glance. I just need to confirm the changes to the sudo paths internally.

[averche]

This looks reasonable to me. I've tried out the steps to reproduce the issue and the fix and both work! Thanks again for contributing, @maxb!

I'll let @hghaf099 confirm the sudo path logic and merge the PR.

[maxb]

@maxb I will be reviewing this PR. Thanks for putting it together. It looks great from the first glance. I just need to confirm the changes to the sudo paths internally.

@hghaf099 Please let me know if there is any evidence I can gather and add to this PR to assist with this process?

It would be great to get it in before its 6-month anniversary, and then I can move on to trying to attract a HashiCorp sponsor to some of my other open PRs.

[hghaf099]

Looks great!