Resolve "Tests SectionPage"

Closes #227 (closed)

Additional component changes in the cleanup:

• Added a speciesIds-computed property (DRY) and removed unused data-property with same name
• Removed unused this.transect
• Removed unused Icon
• Removed unused CSS rules
• Use useTransects instead of TransectService to fetch the transect from local storage
• Moved data into data property (sections, currentSectionEvents etc.)
• Replaced computational expensive line (this.species = usedSpeciesIds.map(this.getSpeciesById).filter(it => it !== undefined) as SpeciesListItem[]) - to only update species which aren't already in this.species
• Shifted v-for from ion-list into speciesCard to prevent multiple lists (instead of multiple items in a single list)
• Adjusted component name and SectionPageData name (data type interface)
• Sorted imports
• Slight refactoring of useButterflyList and useTransects