[Dashboards as code] consolidate URL BWC and add functional tests (#221989)

Closes https://github.com/elastic/kibana/issues/221683

PR does the following
* Consolidates `SharedDashboardState` and `DashboardLocatorParams` types
into a single type `DashboardLocatorParams`.
* Combine URL parsing and locator parsing into single function,
`extractDashboardState`. Previously this was done in 2 seperate code
paths: `loadDashboardHistoryLocationState` for locator state and
`loadAndRemoveDashboardState` for URL state.
* `extractDashboardState` takes `unknown` instead of
`DashboardLocatorParams`. Input value could contain legacy versions of
`DashboardLocatorParams` or really anything since its provided in the
URL by users. `unknown` better reflects that the input could be a lot of
different things.
* `extractDashboardState` uses duck typing to try its best to convert
from legacy versions of `DashboardLocatorParams` to current
`DashboardState` type
* Replaced `bwc_shared_urls` functional test with unit tests
* Added function test `bwc_short_urls` functional tests to ensure stored
URLs continue to work. Added tests for 8.14, 8.18, and 8.19 URL state.

---------

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>
Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>
Co-authored-by: Devon Thomson <devon.thomson@elastic.co>

packages/kbn-optimizer/limits.yml

@@ -20,7 +20,7 @@ pageLoadAssetSize:
   console: 61298
   contentConnectors: 65000
   contentManagement: 16254
-  controls: 12000
+  controls: 13000
   core: 564663
   crossClusterReplication: 65408
   customIntegrations: 22034