Add arguments to record_level_table for easy filtering of cite_label and cite_string

[TNRiley]

Currently, a user must add further script to filter the record level table. Adding an argument to allow users to easily specify which data they want to see in the table would be helpful. I believe all we would need to do is this. @LukasWallrich thoughts on this?

NOTE: currently this shows citations, but actually it would be unique_citations per #190

# add parameters
cite_label_include = NULL, cite_string_include = NULL

AND

# add filter logic
# Filter citations if cite_label_include is provided
if (!is.null(cite_label_include)) {
  citations <- citations %>%
    dplyr::filter(stringr::str_detect(cite_label, cite_label_include))
}

# Filter citations if cite_string_include is provided
if (!is.null(cite_string_include)) {
  citations <- citations %>%
    dplyr::filter(stringr::str_detect(cite_string, cite_string_include))
}