fix(react): stop passing selectionMode through as a prop

[s100]

Closes #5903.

In <ContentSwitcher> and <Tabs>, the selectionMode is no longer passed as a prop to the inner <div>.

Testing / Reviewing

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Unit tests have been added to demonstrate this issue. Reviewers can also view these components in Storybook and see that the errors in question have gone away. However, you might consider altering your unit testing so that all errors of this kind cause a failure automatically.

[s100]

Incidentally, while following the contribution instructions, I found that yarn build consistently fails like so:

@carbon/themes:  INFO  Creating sassdoc markdown for pattern: 'scss/**/*.scss', ignoring: ''
@carbon/themes: » [WARNING] Item `carbon--theme` is an alias of `carbon--theme--white` but this item doesn't exist.
@carbon/themes:  SUCCESS  Done! �
@carbon/pictograms-react:  INFO  Writing to destination
@carbon/icons:  INFO  Building JavaScript modules...
@carbon/icons: [Error: EMFILE: too many open files, open 'C:\Users\s100\Documents\WebstormProjects\carbon\packages\icons\lib\t
ext--new-line\16.js'] {
@carbon/icons:   errno: -4066,
@carbon/icons:   code: 'EMFILE',
@carbon/icons:   syscall: 'open',
@carbon/icons:   path: 'C:\\Users\\s100\\Documents\\WebstormProjects\\carbon\\packages\\icons\\lib\\text--new-line\\16.js'
@carbon/icons: }
@carbon/icons: error Command failed with exit code 1.
@carbon/icons: info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
lerna ERR! yarn run build exited 1 in '@carbon/icons'
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

Any clue what causes this?

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[emyarod]

looks good to me. I'm able to replicate the EMFILE build failure only on Windows, and I think we can open that as a separate issue