Hide export icon if activity empty

[myxmaster]

Description

This fixes #2559.

This pull request is categorized as a:

• [ ] New feature
• [ ] Bug fix
• [ ] Code refactor
• [ ] Configuration change
• [ ] Locales update
• [ ] Quality assurance
• [x] Other

Checklist

• [ ] I’ve run yarn run tsc and made sure my code compiles correctly
• [x] I’ve run yarn run lint and made sure my code didn’t contain any problematic patterns
• [x] I’ve run yarn run prettier and made sure my code is formatted correctly
• [x] I’ve run yarn run test and made sure all of the tests pass

Testing

If you modified or added a utility file, did you add new unit tests?

• [ ] No, I’m a fool
• [ ] Yes
• [x] N/A

I have tested this PR on the following platforms (please specify OS version and phone model/VM):

• [x] Android
• [ ] iOS

I have tested this PR with the following types of nodes (please specify node version and API version where appropriate):

• [x] Embedded LND
• [ ] LND (REST)
• [ ] LND (Lightning Node Connect)
• [ ] Core Lightning (CLNRest)
• [ ] LndHub
• [ ] [DEPRECATED] Core Lightning (c-lightning-REST)
• [ ] [DEPRECATED] Core Lightning (Spark)
• [ ] [DEPRECATED] Eclair

Locales

• [ ] I’ve added new locale text that requires translations
• [ ] I’m aware that new translations should be made on the ZEUS Transfix page and not directly to this repo

Third Party Dependencies and Packages

• [ ] Contributors will need to run yarn after this PR is merged in
• [ ] 3rd party dependencies have been modified:
  • verify that package.json and yarn.lock have been properly updated
  • verify that dependencies are installed for both iOS and Android platforms

Other:

• [ ] Changes were made that require an update to the README
• [ ] Changes were made that require an update to onboarding