The default output filenames should match the name of the `.yarn` file

[weaversam8]

ysc version 1 correctly inferred the name of the output files from the input .yarn file when running ysc compile. For example, ysc compile file.yarn would output file.yarnc and file.csv.

ysc version 2 adds the ability to provide the name of the output files as command line flags (--output-name and --output-string-table-name) which is great, but defaults to a less descriptive name (Output.yarnc and Output.csv respectively.) The default output name should be determined from the name of the .yarn file.