Start adding ValueSet lookup to search functionality

[katyasoup]

What this PR does:

• Updates search functionality to recognize the resource type selected in the dropdown menu (defaults to "All")
• When "Value Set" or "All" is selected, query the db for ValueSets* that match the input (string, id, or oid)
  • Update the table view to display ValueSet-specific column headers and data (per Figma mockup)
• Only when "Code System" is selected, query the db for CodeSystems that match the input
  • Display CodeSystem-specific column headers and data (as earlier code did)
• Adjust the "SearchResultRow" struct to contain result counts and additional data types
• Dynamically render the appropriate template based on SearchResultRow data passed to SearchResult.templ
• Adds new templates for ValueSet results (result, result row, table header, result count)

What this PR doesn't do:

• Does not support resource lookups for resources other than ValueSet and CodeSystem
  • All currently queries the ValueSet table only, not all resources
• For ValueSet searches, the column Version is hard-coded; will need a join on value_set_version to get accurate data returned
• Also for ValueSet searches, "effective date" is populated with data from the statusdate column; need data from value_set_version table to get effective date
• As with the initial CodeSystem result UI, pagination/download button/etc. are currently non-functional
• Templates could be organized better; I'd like to follow up in a separate PR to rework existing templates to be more re-usable between resource types