support study and pipeline to get_coding_ssm

[Kdreval]

This is to resolve #95
Here is a minimal rep example:

metadata <- get_gambl_metadata(
    seq_type_filter = "capture"
) %>%
filter(cohort == "dlbcl_reddy")

maf_slms3 <- get_coding_ssm(
    this_seq_type="capture",
    these_samples_metadata = metadata
)

maf_original <- get_coding_ssm(
    this_seq_type="capture",
    these_samples_metadata = metadata,
    tool_name = "publication"
)

> table(maf_slms3$Pipeline)

SLMS-3 
 13833 
> table(maf_original$Pipeline)

Publication 
       4739