Business Dashboard UI: should provide Return URL when redirecting to log in

**Describe the bug in current situation**
If the user goes directly to their business dashboard (eg, from a bookmark, or a link in an email), they are redirected to log in. However, no Return URL is provided, so they don't return to their business dasboard. They will have to use the bookmark again or click the email link again.

This previously worked in Entity Dashboard UI (Filings UI) but appears to have been dropped when that was rewritten in Nuxt as Business Dashboard UI.

**Link bug to the User Story**
None.

**Impact of this bug**
We are missing an opportunity to provide a smooth flow for our users. In fact, we tell users "click here to go to your business dashboard" but it doesn't always work.

Users will have to go to their bookmark again, or click an email again, to get to their business dashboard after logging in.

**Chance of Occurring (high/medium/low/very low)**
High.

**Pre Conditions: which Env, any pre-requesites or assumptions to execute steps?**
User must not be logged in, then must try to navigate directly to their business dashboard.

**Steps to Reproduce**
Steps to reproduce the behavior:
1. make sure you are not logged in
2. click a bookmark, or link in an email, to go to your business dashboard
3. observe that you are prompted to log in -- do so
4. observe that you are not returned to your business dashboard -- you are instead directed to the main page

**Actual/ observed behavior/ results**
You are not returned to your business dashboard -- you are instead directed to the main page.

**Expected behavior**
After logging in, you are returned to your business dashboard.

**Screenshots/ Visual Reference/ Source**
Not applicable.

**Root Cause Analysis (RCA) results**
This previously worked in Entity Dashboard UI (Filings UI) but appears to have been dropped when that was rewritten in Nuxt as Business Dashboard UI.