Change style of primary buttons

According to React Native Paper docs, the purpose
of the "contained" mode of button is for the primary
action.

https://callstack.github.io/react-native-paper/docs/components/Button/#mode

EditExercises.tsx

@@ -189,7 +189,7 @@ export default function EditExercises() {
         </ScrollView>
         <Button
           disabled={!name}
-          mode="outlined"
+          mode="contained"
           icon="content-save"
           onPress={update}
         >

EditPlan.tsx

@@ -193,7 +193,7 @@ export default function EditPlan() {
 
         <Button
           disabled={exercises.length === 0 && days.length === 0}
-          mode="outlined"
+          mode="contained"
           icon="content-save"
           onPress={async () => {
             await save();

EditSet.tsx

@@ -334,7 +334,7 @@ export default function EditSet() {
 
       <Button
         disabled={!name}
-        mode="outlined"
+        mode="contained"
         icon="content-save"
         style={{ margin: MARGIN }}
         onPress={handleSubmit}

EditSets.tsx

@@ -187,7 +187,7 @@ export default function EditSets() {
       </View>
 
       <Button
-        mode="outlined"
+        mode="contained"
         icon="content-save"
         style={{ margin: MARGIN }}
         onPress={save}

EditWeight.tsx

@@ -151,7 +151,7 @@ export default function EditWeight() {
 
       <Button
         disabled={!value}
-        mode="outlined"
+        mode="contained"
         icon="content-save"
         style={{ margin: MARGIN }}
         onPress={submit}

StartPlan.tsx

@@ -231,7 +231,7 @@ export default function StartPlan() {
             />
           )}
         </View>
-        <Button mode="outlined" icon="content-save" onPress={handleSubmit}>
+        <Button mode="contained" icon="content-save" onPress={handleSubmit}>
           Save
         </Button>
       </View>