Allow filtered lists to preprocess the filter string

An example for this can be seen in the next commit.

We make this a setter rather than an added constructor argument so that we don't
have to change all those contexts that don't want to make use of this.

pkg/gui/context/filtered_list.go

@@ -14,6 +14,7 @@ type FilteredList[T any] struct {
 
 	getList          func() []T
 	getFilterFields  func(T) []string
+	preprocessFilter func(string) string
 	filter           string
 
 	mutex deadlock.Mutex
@@ -26,6 +27,10 @@ func NewFilteredList[T any](getList func() []T, getFilterFields func(T) []string
 	}
 }
 
+func (self *FilteredList[T]) SetPreprocessFilterFunc(preprocessFilter func(string) string) {
+	self.preprocessFilter = preprocessFilter
+}
+
 func (self *FilteredList[T]) GetFilter() string {
 	return self.filter
 }
@@ -79,7 +84,12 @@ func (self *FilteredList[T]) applyFilter(useFuzzySearch bool) {
 	self.mutex.Lock()
 	defer self.mutex.Unlock()
 
-	if self.filter == "" {
+	filter := self.filter
+	if self.preprocessFilter != nil {
+		filter = self.preprocessFilter(filter)
+	}
+
+	if filter == "" {
 		self.filteredIndices = nil
 	} else {
 		source := &fuzzySource[T]{
@@ -87,7 +97,7 @@ func (self *FilteredList[T]) applyFilter(useFuzzySearch bool) {
 			getFilterFields: self.getFilterFields,
 		}
 
-		matches := utils.FindFrom(self.filter, source, useFuzzySearch)
+		matches := utils.FindFrom(filter, source, useFuzzySearch)
 		self.filteredIndices = lo.Map(matches, func(match fuzzy.Match, _ int) int {
 			return match.Index
 		})