This PR does the following:

1. Implements parse_tsv() and parse_csv() as aliases for parse_sssom_table that don't try and guess the right separator, which makes it easier to understand exactly what the function is for
2. Guts and rewrites private separator inference and file opening utilities
3. Exposes functions for parsing SSSOM at the top level, i.e. so you can do sssom.parse_tsv() instead of needing to know it's hiding in sssom.writers.parse_tsv
4. Get rid of the sssom.parse function which just wraps pd.read_csv(), and is only used by a test
5. Quality of life improvement: enables all write functions to take in a file path (in addition to being able to taking a TextIO)
6. Update README to show off high level I/O functionality in a "getting started" section
7. Improve docs and typing

Demo

import sssom

# other SSSOM files can be found on https://mapping-commons.github.io
url = "https://raw.githubusercontent.com/mapping-commons/mh_mapping_initiative/master/mappings/mp_hp_eye_impc.sssom.tsv"

# TSV can be parsed into a mapping set dataframe object,
# which includes a pandas DataFrame, a curies.Converter,
# and metadata
msdf = sssom.parse_tsv(url)

# SSSOM comes with several "write" functions
sssom.write_tsv(msdf, "test.tsv")
sssom.write_json(msdf, "test.json")
sssom.write_owl(msdf, "test.owl")
sssom.write_rdf(msdf, "test.ttl")