Move button parallel with the field for greater visibility

Problem/Motivation

Our editors are not seeing the button that loads the modal of the tree view.

At first we considered adding Description text to the field, but then we decided on moving the button parallel to the field. Like this:

We like this change and we're posting it as an issue in case others like it too.

Steps to reproduce

1. Load the module.
2. Create a vocabulary.
3. Add a term to the vocabulary. (This step may not be necessary.)
4. Add a Taxonomy term field to the content type.
5. Create content of the content type.
6. Note the button is below the field.

Proposed resolution

By moving the button parallel to the field, our hope is our editorial staff will see, click, and use the button when selecting terms. Note this patch works well with the Claro admin theme, not the Seven admin theme.

Remaining tasks

See patch.

User interface changes

Changes the placement of the button that loads the modal of the tree view.

API changes

None.

Data model changes

None.