Merged PRs

• 1169: go/libraries/doltcore/sqle: Keyless tables don't have PK index -- fix describe panic
• 1167: C# test for alternate MySQL connector library, upgraded existing to u…
  …se dotnet 5 (up from 3)
• 1162: unrolled decode varint decode loop
  30% faster on the benchmark in this PR.
  BenchmarkUnrolledDecodeUVarint/binary.UVarint-8 1000000000 0.0372 ns/op
  BenchmarkUnrolledDecodeUVarint/unrolled-8 1000000000 0.0258 ns/op
• 1159: Bh/hang fix
  Fixes #1153
  and disables GC on import errors.
• 1157: Address escaping in longtext/json
  Longext is no longer being exported properly in json and csv. This pr fixes that. Cc linked comment.
• 1151: Implement dolt status table
  Implement the dolt_status table. Schema is of the form table_name, staged(bool), status,
• 1149: /go/libraries/doltcore/sqle: move table cache to DoltSession, purge on root change
  I'm ambivalent about where the table cache lives, but we need to have access to it when we change the root of a sqle.Database
  This PR purges the table cache when we change roots. IE SET @@dolt_head = hashof(...). The intention is to limit the scope of edit sessio
  ns, and table mutations in general, and contain them to the working root of a sqle.Database.
  Currently there is a tricky reference chain within the table cache: sqle.tableCache -> sqle.WritableDoltTable -> sqle.sqlTableEditor
  -> table/editor.TableEditSesson
  When we change roots in the database we also change the root within the TableEditSession. They're both referencing the new working root.
  Without purging the cache, we will keep old tables from the previous working root that still have a reference to the TableEditSession.
  This hasn't caused any issues (yet), but I think it's prudent to limit the scope and lifetime of these interconnected pieces of state. The
  next step is to create a fresh TableEditSession each time we switch roots.
• 256: added describe queries for keyless tables
• 255: This function implement an Naryfunction type.
  Allows you to define sqle functions that have multiple children.
• 254: Fixed UNHEX/HEX roundtrip
  Simple fix but I ended up completely reevaluating our binary type implementation. Fixed a bug found in the cast package we were using to
  convert strings, and also changed UNHEX to return the proper SQL type.
• 252: Added hash functions
• 249: Alias bug fixes
  Fixes a number of buggy behaviors involving column indexes and table name resolution.

Closed Issues

• 1161: Primary keyless tables seem to break DESCRIBE
• 1153: p.StopWithErr(err) is hanging on large imports