Add ability to define custom aliases for refSeq names

[shashankbrgowda]

Fixes #418

Rendering of havana evidence track is working as expected after configuring the reference name alias.

[garrettjstevens]

I think we can update the aliases on the client by doing something like this in executeOnClient():

async executeOnClient(dataStore: ClientDataStore) {
  if (!dataStore) {
    throw new Error('No data store')
  }
  const { assemblyManager } = getSession(dataStore)
  const assembly = assemblyManager.get(this.assembly)
  assembly.configuration.refNameAliases.set(this.refSeqAliases)
}