i18n support

[saulipurhonen]

Description

Introduced i18n support with react-i18next library.
Selection is stored in local storage. This helps to render correct translation when user chooses locale on login page.

Related issues

Closes #21

Type of change

• New feature (non-breaking change which adds functionality)

Changes Made

• Added i18n configuration file to src path
• Language selector on top navigation with MUI Menu component
• Store locale selection to browsers local storage and redux state
• Utility function for navigating with selected locale
• Changed navigation items to navigate with locale
• Added translation files to src/translations
• Translated "Logged in as" string on /home route.
• Added fallback for user templates in UserDraftTemplates. This caused some issues if templates resulted as undefined

Testing

• E2E

[saulipurhonen]

Initial approach was to use React Routers basename as dynamic base URL and this way to reduce the need to insert locale on link paths. However dynamic basename isn't supported and only way I got it working was to restart the whole app. This would stray away from seamless design and would reset the redux state.

Therefore I decided to go with local storage / locale in redux state combination.

[saulipurhonen]

Issue #21 includes feature requests for both JSON schema based forms and AJV validation.
To reduce weight on this PR I think we should do these two on separate PR's.

[hannyle]

For me the components inside <NewDraftWizard/> seem not completely worked with translation. For example, WizardCreateFolderStep is missing the query params when changing language.

[saulipurhonen]

For me the components inside <NewDraftWizard/> seem not completely worked with translation. For example, WizardCreateFolderStep is missing the query params when changing language.

Query parameters are now included in language change method.

[lilachic]

LGTM. This contains a lot just to introduce locale for a another language. I'm not sure if its relevant but clicking En/Fi button in listing of folder content and details visible with "Show details" make the details hidden. For example http://localhost:3000/fi/home/published/{some id here}

[saulipurhonen]

I'm not sure if its relevant but clicking En/Fi button in listing of folder content and details visible with "Show details" make the details hidden. For example http://localhost:3000/fi/home/published/{some id here}

Good call. This happens because language change updates locale in redux state and therefore the app re-renders components in navigation tree. Re-rendering is needed to get translations but I think that the opened details should be visible after language change. I'll look into it.

[saulipurhonen]

I'm not sure if its relevant but clicking En/Fi button in listing of folder content and details visible with "Show details" make the details hidden. For example http://localhost:3000/fi/home/published/{some id here}

Good call. This happens because language change updates locale in redux state and therefore the app re-renders components in navigation tree. Re-rendering is needed to get translations but I think that the opened details should be visible after language change. I'll look into it.

This should be fixed now.