MM42267: Add member count in the browse channel modal (#23800)

* add base for calling the endpoint

* add endpoint and handler

* update store and layers

* call the endpoint

* align types

* update app layers

* generate mocks

* complete handler

* finish store query

* add todos

* add ui for member count

* add selector

* add a todo

* add cache layer

* optimize calls in FE

* handle invalidation of the cache

* fix go style

* fix test

* use existing channel layer count

* fix import error

* delete unnecessary code

* write tests for channel cache layer

* fix testname

* fix mocks

* fix cache layer test

* fix a test

* really fix the test

* write more tests for server

* address PR comments

* remove comment

* rename more_channels to browse_channels

* fix style

* update snapshot

* add translations

* Revert "add translations"

This reverts commit 56476a5dabe357703ef02be9a38b3e88f5c8b1e7.

* add only related translations

* address PR review points

* add test

* fix test

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

e2e-tests/cypress/tests/integration/channels/channel_sidebar/new_channel_dropdown_spec.ts

@@ -68,13 +68,13 @@ describe('Channel sidebar', () => {
         cy.get('.AddChannelDropdown .MenuItem:contains(Browse channels) button').should('be.visible').click();
 
         // * Verify that the more channels modal is visible
-        cy.get('#moreChannelsModal').should('be.visible');
+        cy.get('#browseChannelsModal').should('be.visible');
 
         // Click the Off-Topic channel
         cy.findByText('Off-Topic').should('be.visible').click();
 
         // Verify that new channel is in the sidebar and is active
-        cy.get('#moreChannelsModal').should('exist');
+        cy.get('#browseChannelsModal').should('exist');
         cy.url().should('include', `/${teamName}/channels/off-topic`);
         cy.get('#channelHeaderTitle').should('contain', 'Off-Topic');
         cy.get('.SidebarChannel.active:contains(Off-Topic)').should('be.visible');