Create pVACsplice wdl on analysis wdl

To-do:

1. create analysis-wdls/definitions/tools/regtools.wdl
2. create analysis-wdls/definitions/tools/pvacsplice.wdl
3. create analysis-wdls/definitions/subworkflows/pvacsplice.wdl

Compare pvacseq and pvacsplice inputs
+ pvacseq: 
a) annotated vcf (require WT, frameshift pluggin)
b) phased vcf

+ pvacsplice : 
a) annotated vcf (doesnt require frameshift pluggin)
b) regtools tsv
c) reference fasta 
d) reference gtf

Both require MHC alleles

pvacsplice (vs pvacseq):

• requires reference fasta (reference dna fasta, not to be confused with peptide_fasta)
• requires reference gtf
• requires regtools tsv (splice variants, splice sites, read counts for splice variants)
• doesnt predict MHC anchor location (since there's no matched WT)