Currently, the databases page automatically loads stats and info
on all tables in all database simultaneously. This can cause heavy
load and contention on clusters with hundreds of tables and/or
databases.

This change introduces a quick fix to prevent the immediate problem
with the expectation that we will revisit the databases page for
a more thorough redesign in the near future.

This change adds a button next to each database in the
databases page titled "Load stats for all tables" which triggers
the queries to load table-specific stats for just that one database.
The tables will be loaded in sequence by converting the loading
loop to use async/await to ensure one query is executed at a time.

One problem this introduces is that the database stats summary
box on the right computes its data incrementally and will show
changing data as more tables load for a specific database. We have
chosen to not show the updated data until all table info has been
loaded for the given database.

Release note (admin ui change): Loading table-level stats requires
a button click per-database in order to prevent contention for
clusters with many databases and/or tables. In addition, the loading
of table data is staggered by table instead of triggered simultaneously
for all tables.