Replace Additional search views path parameters with query parameters

[obulat]

Problem

Additional search views on the frontend should use the query parameters instead of the path parameters.

Description

The following changes are necessary:

• replace /pages/<mediaType>/tag/_tag.vue and /pages/<mediaType>/source/_.vue pages with /pages/<mediaType>/collection.vue. The page should be similar to _tag.vue, using the collection middleware. It should not be setting the collection state in the setup function
• update collection.ts middleware to extract the collection parameters from the route name and query parameters. It should also check that the source name is valid, and should update the search store state.
• replace path-related functions in the search store to parse or set the collection query parameters.

Additional context

Temporarily, until the API changes are added, we can use the current full-text search query parameters for the query: tags for tag view, creator and source for the creator and source. The unstable__collection parameter will be ignored by the API for now.

The changes were discussed in Rethinking additional search views URLs