Allow localized strings

[DeTuksa]

This PR provides the option of using localised strings and an example of how to go about setting up your custom strings in your app

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• I read the [Flutter Style Guide] recently, and have followed its advice.
• I signed the [CLA].
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is [test-exempt].
• All existing and new tests are passing.

[csells]

requested @domesticmouse as my support contract is limited to P0s (@mit-mit can decide if this is P0).

[domesticmouse]

This PR does several things at once. By my reading it:

• Updates the base version of Flutter used
• Adds dependencies
• Adds localised strings

Can we split these into separate PRs?

[DeTuksa]

Is this better @domesticmouse?

[domesticmouse]

Please fix up CI errors