new function: build tag tables for find_tags_motus from motus-metadata-history commit hash

[jbrzusto]

In order to make tag finder output reproducible and to allow comparison between different choices of tagfinder parameters, we need to be able to take the metadata-history commit hash recorded for any run of the tag finder and rebuild the tags and tagDeps tables that tagfinder run used.
Something like this:

rebuildHistoricalTagDB = function (metadataCommit, dbName) {
#' @param metadataCommit:  git commit hash from
#' the repo at https://github.com/jbrzusto/motus-metadata-history
#'
#' @param dbName: full path to sqlite database in which to rebuild 
#' the `tags` and `events` tables corresponding to the tag deployments
#' from `metadataCommit`.  The DB is created if it does not exist.
#'
#' @return logical scalar; TRUE on success, FALSE otherwise.
...
}