Category: Hide "Repost" from ContentType filter, except for WildWest

## Ticket
1368
> can we remove the repost filter option on categories outside of wildwest/following?

## Approach
Using `context` to:
- reduce the amount of files that need to change.
- avoid prop-drilling.
- allow the ability to dynamically define the Filter's allowed values in a contained manner.

Clients that don't need customization simply does not need to wrap their component with the context.

The context only contains Content Type for now, but can include anything that future clients need to dynamically adjust.

.flowconfig

@@ -16,6 +16,7 @@
 suppress_comment=\\(.\\|\n\\)*\\$FlowFixMe
 suppress_comment=\\(.\\|\n\\)*\\$FlowIssue
 module.name_mapper='^constants\(.*\)$' -> '<PROJECT_ROOT>/ui/constants\1'
+module.name_mapper='^contexts\(.*\)$' -> '<PROJECT_ROOT>/ui/contexts\1'
 module.name_mapper='^util\(.*\)$' -> '<PROJECT_ROOT>/ui/util\1'
 module.name_mapper='^redux\(.*\)$' -> '<PROJECT_ROOT>/ui/redux\1'
 module.name_mapper='^types\(.*\)$' -> '<PROJECT_ROOT>/ui/types\1'

ui/component/claimListHeader/view.jsx

@@ -11,6 +11,7 @@ import { FormField } from 'component/common/form';
 import Button from 'component/button';
 import { toCapitalCase } from 'util/string';
 import SEARCHABLE_LANGUAGES from 'constants/searchable_languages';
+import { ClaimSearchFilterContext } from 'contexts/claimSearchFilterContext';
 
 type Props = {
   defaultTags: string,
@@ -62,6 +63,7 @@ function ClaimListHeader(props: Props) {
     languageSetting,
     scrollAnchor,
   } = props;
+  const filterCtx = React.useContext(ClaimSearchFilterContext);
   const { action, push, location } = useHistory();
   const { search } = location;
   const [expanded, setExpanded] = usePersistedState(`expanded-${location.pathname}`, false);
@@ -345,7 +347,7 @@ function ClaimListHeader(props: Props) {
                       })
                     }
                   >
-                    {CS.CONTENT_TYPES.map((type) => {
+                    {filterCtx.contentTypes.map((type) => {
                       if (type !== CS.CLAIM_CHANNEL || (type === CS.CLAIM_CHANNEL && !channelIdsParam)) {
                         return (
                           <option key={type} value={type}>

ui/contexts/claimSearchFilterContext.jsx

@@ -0,0 +1,9 @@
+import React from 'react';
+import * as CS from 'constants/claim_search';
+
+export const ClaimSearchFilterContext = React.createContext({
+  contentTypes: CS.CONTENT_TYPES,
+  // --Future expansion:
+  // durationTypes: CS.DURATION_TYPES,
+  // ...
+});

ui/page/discover/view.jsx

@@ -8,6 +8,7 @@ import * as CS from 'constants/claim_search';
 import Page from 'component/page';
 import ClaimListDiscover from 'component/claimListDiscover';
 import Button from 'component/button';
+import { ClaimSearchFilterContext } from 'contexts/claimSearchFilterContext';
 import useHover from 'effects/use-hover';
 import { useIsMobile } from 'effects/use-screensize';
 import analytics from 'analytics';
@@ -19,6 +20,8 @@ import I18nMessage from 'component/i18nMessage';
 import moment from 'moment';
 import LivestreamSection from './livestreamSection';
 
+const CATEGORY_CONTENT_TYPES_FILTER = CS.CONTENT_TYPES.filter((x) => x !== CS.CLAIM_REPOST);
+
 type Props = {
   dynamicRouteProps: RowDataItem,
   location: { search: string },
@@ -77,6 +80,10 @@ function DiscoverPage(props: Props) {
   }
 
   const includeLivestreams = !tagsQuery;
+  const filters = { contentTypes: isCategory && !isWildWest ? CATEGORY_CONTENT_TYPES_FILTER : CS.CONTENT_TYPES };
+
+  // **************************************************************************
+  // **************************************************************************
 
   function getMeta() {
     if (!dynamicRouteProps) {
@@ -191,6 +198,7 @@ function DiscoverPage(props: Props) {
       fullWidthPage={tileLayout}
       className={classnames('main__discover', { 'hide-ribbon': hideRepostRibbon })}
     >
+      <ClaimSearchFilterContext.Provider value={filters}>
         <ClaimListDiscover
           pins={getPins(dynamicRouteProps)}
           hideFilters={isWildWest ? true : undefined}
@@ -223,6 +231,7 @@ function DiscoverPage(props: Props) {
           forceShowReposts={dynamicRouteProps}
           searchLanguages={dynamicRouteProps?.options?.searchLanguages}
         />
+      </ClaimSearchFilterContext.Provider>
     </Page>
   );
 }