fix: do not show help modal when confirm modal is already opened

[dundee]

fixes #233

[codecov[bot]]

Codecov Report

Patch coverage: 90.62% and project coverage change: -0.07 :warning:

Comparison is base (e18c125) 94.13% compared to head (8532b8c) 94.07%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #237 +/- ## ========================================== - Coverage 94.13% 94.07% -0.07% ========================================== Files 29 29 Lines 2746 2768 +22 ========================================== + Hits 2585 2604 +19 - Misses 123 125 +2 - Partials 38 39 +1 ``` | [Impacted Files](https://codecov.io/gh/dundee/gdu/pull/237?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniel+Milde) | Coverage Δ | | |---|---|---| | [tui/keys.go](https://codecov.io/gh/dundee/gdu/pull/237?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniel+Milde#diff-dHVpL2tleXMuZ28=) | `96.49% <90.62%> (-1.09%)` | :arrow_down: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniel+Milde). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniel+Milde)

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