Fixed project filter method and event issues

[ilyboc-bak]

1. Project filtering is not working because the event name which is 'change' overlaps with the default event of the select element. So by changing it to something else like 'filter', the payload can get emitted successfully (ProjectGrid.vue & ProjectFilter.vue)
2. The filterProjectsByCategory method should use filter instead of map (ProjectGrid.vue)
3. Refactored selectedProject to selectedCategory (ProjectGrid.vue)

[netlify]

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