[MM-9698] Fix routes to have basic info before rendering channel_view

[sudheerDev]

Summary

Fix routes to have basic info before rendering channel_view.
Fixes duplicate call of posts on route switch.

Ticket Link

Related Issue
Related ticket

present routes.

• Channel Route: /channels/{channel_name}
• GM Route: /messages/{group_id}
• DM Route: /messages/@{username}
• Fallback Route: /channels/{default_channel_name}

legacy routes for redirection.

• /channels/{channel_id} -> Channel Route
• /channels/{id1}__{id2} -> DM Route
• /messages/{user_id} -> DM Route
• /messages/{user_email} -> DM Route
• /channels/{group_id} -> GM Route

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• Ran make check-style to check for style errors (required for all pull requests)
• Ran make test to ensure unit and component tests passed
• Added or updated unit tests (required for all new features)
• Has UI changes
• Touches critical sections of the codebase (auth, posting, etc.)

[sudheerDev]

@hmhealey Hey i have merged channel and group routes to remove duplicate code. It would be great if you can give some initial feedback.

From ticket

The bugs that have come up for the issue have either been because the URL rewriting failed or the URL rewriting was done without actually changing the channel internally, so it would be nice to make sure that those are always done

I made sure that the respective channel is loaded and saved before changing the URl or loading the channel_view so we dont load a wrong channel or make duplicate requests.

Let me know your thoughs on it.

[sudheerDev]

i will add asGroup default param to false

[hmhealey]

Ensuring the user/channel is loaded before switching looks good, but I'm not entirely sure how this will make testing easier since that was the main thing I was hoping out of from this ticket. It's a good start though

[hmhealey]

This should probably be a getChannel API call since you can't join a group channel after its been created

[hmhealey]

If you make the part of this that gets the channel from the store into a redux action, you'll be able to avoid using ChannelStore here. That action would look something like

import {getChannel} from 'mattermost-redux/selectors/channels';

function getChannelByIdentifier(identifier, identifierType) {
    return async (dispatch, getState) => {
        let channel;
        if (identifierType === 'name') {
            channel = getChannelByName(getState(), identifier);

            if (!channel) {
                response = await joinChannel(...);
            }
        }

        if (channel) {
            return {data: channel};
        } else {
            return response;
        }
    };
}

[hmhealey]

It would also be nice to avoid the ChannelStore here as well

[hmhealey]

Similar feedback to the ChannelGroupRoute here with suggestions on how to refactor this