Compile and report on all errors in getSiteId()

[ck37]

Hello,

This is a PR that revises getSiteId() to compile all errors and report them at the end, rather than stop at the first error. I found it a little time consuming when I was initially getting my 4CE data setup to get the incremental errors, so I believe this could be a helpful revision for others as well. Happy to make any changes if desired.

This is what the output looks like before making any revisions to the BIDMC data exports:

Error(s) found in getSiteId():
 * No match found for file name pattern: Labs-.+\.csv
 * No match found for file name pattern: Medications-.+\.csv
 * No match found for file name pattern: Diagnoses-.+\.csv
 * No match found for file name pattern: Demographics-.+\.csv
 * No match found for file name pattern: DailyCounts-.+\.csv
 * No match found for file name pattern: ClinicalCourse-.+\.csv 
Error in FourCePhase2.1Data::getSiteId() : 
  Could not complete getSiteId(). See https://github.com/covidclinical/Phase2.1DataRPackage for help.

Thanks,
Chris