resurrect build_user_query or permit user query building in build_query

[cjbarrie]

The function build_user_query() in v0.1.0 allowed users to build user queries, taking a vector of usernames, and searching their tweets while e.g. removing RTs or specifying other parameters. This was deprecated in recent PR.

For consistency, we need to resurrect build_user_query() or make it possible to take a vector of usernames with the build_query() function and append the additional tweet parameters to each username.

The expected behaviour (as it behaves in the current CRAN release) is as follows:

require(academictwitteR)
#> Loading required package: academictwitteR

bt <- "AAAAAAAAAYOURBEARERTOKENHERE"

users <- c("cbarrie", "justin_ct_ho")

users_params <-
  build_user_query(users,
                   is_retweet = F,
                   has_media = T,
                   lang = "en")

users_params
#> [1] "cbarrie -is:retweet has:media lang:en"     
#> [2] "justin_ct_ho -is:retweet has:media lang:en"