Issue-22 Add Share plan button on the Plan page

[pankova]

Closes #22
The added sharing icon is from SF Symbols app. For this reason, there is no need to add an author info.
I've removed the ic_action_share icon, as it doesn't seem to be used in the project. If in doubt, I can return.

Testing

• Device: iPhone 12 mini, iOS15.5
• Simulator. I have M1 notebook, I couldn't test on the simulator

Checks

• Export empty plan

Plan

Warning Signs
–

Coping Strategies
–

Reasons to Live
–

Contacts
–

Places for Distraction
–

Other
–

• Export plan with the Other section filled in

Plan

Warning Signs
–

Coping Strategies
–

Reasons to Live
–

Contacts
–

Places for Distraction
–

Other
Test filled section

• Export plan with the first five items filled in (see below)

Important
I couldn't check the plan with the first five items filled in, because new Xcode 13.2.1 / 13.4.1 builds with some UI bugs:

1. Transparent splash screen
2. Transparent navigation bar till I scroll up the screen

The video with 1 and 2: https://user-images.githubusercontent.com/7028613/182032101-e62f3157-217c-4e1d-a312-3a583481197f.mov

3. Untappable tip textfield and +Add another button.

The reason is new Xcode 13, but I can't install the previous, because macOS Monterey can't work with Xcode earlier, than Xcode 13.

The project needs an issue with adaptation to Xcode 13 – I can create it. As well, It could be useful to decide on supported iOS versions. The current minimum iOS version is 9.
If it's decided to support all older variants, this point can be described in the Readme, as this may raise a question in any issue. In another case, the minimum iOS version could be raised, as this can simplify further development.

[eddielement]

This commit looks great! But you're right, it looks like there's a bunch of weird issues when building the app with the new versions of Xcode. Minimum iOS version can definitely be bumped to iOS 13 to make development easier.