fix(): snackbar issue fix

[GalimzyanovDanil]

Checklist

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [x] Is there an existing issue for this PR? https://github.com/surfstudio/flutter-bottom-sheet/issues/69
• [x] Have the files been linted and formatted?
• [x] Have the docs been updated to match the changes in the PR?
• [x] Have the tests been updated to match the changes in the PR?
• [x] Have you run the tests locally to confirm they pass?

Changes

How does this PR fix the problem?

Since the snackbar is shown relative to the current active scaffold, it was necessary to remove the scaffold from the widget tree, leaving the possibility of displaying the snackbar on top of the bottom sheet. A new parameter was added that allows you to remove the scaffold from the bootom sheet widget tree.

With Scaffold in widget tree.

https://user-images.githubusercontent.com/86564275/216302668-8ac7c46a-517c-498d-ae1a-8a7c1d101e88.mov

Without Scaffold in widget tree.

https://user-images.githubusercontent.com/86564275/216302705-5adec5d6-eefe-4733-9b32-22a140ecb8b5.mov

[dshevchenkoo]

@GalimzyanovDanil exception on analysis check flutter version for package, maybe need to update?

[GalimzyanovDanil]

@GalimzyanovDanil exception on analysis check flutter version for package, maybe need to update?

I can fix depracted fields, but this dont resolve all problems. Also needed upgrade surf_lint_rules package.

[internetova]

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (1c528c9) 100.00% compared to head (3281937) 100.00%.

:exclamation: Current head 3281937 differs from pull request most recent head 8f5833a. Consider uploading reports for the commit 8f5833a to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #76 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 4 4 Lines 254 267 +13 ========================================= + Hits 254 267 +13 ``` | [Files Changed](https://app.codecov.io/gh/surfstudio/flutter-bottom-sheet/pull/76?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=surfstudio) | Coverage Δ | | |---|---|---| | [lib/src/flexible\_bottom\_sheet.dart](https://app.codecov.io/gh/surfstudio/flutter-bottom-sheet/pull/76?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=surfstudio#diff-bGliL3NyYy9mbGV4aWJsZV9ib3R0b21fc2hlZXQuZGFydA==) | `100.00% <100.00%> (ø)` | | | [lib/src/flexible\_bottom\_sheet\_route.dart](https://app.codecov.io/gh/surfstudio/flutter-bottom-sheet/pull/76?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=surfstudio#diff-bGliL3NyYy9mbGV4aWJsZV9ib3R0b21fc2hlZXRfcm91dGUuZGFydA==) | `100.00% <100.00%> (ø)` | |

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