feat: add type hints to methods

[darwinyip]

Having typings in the library would help and saw that there is a PR opened for that. However, the documentation is somewhat lacking.

It is hard to tell what the methods return and are all the parameters while looking at the docs https://googleapis.dev/python/bigquery/latest/generated/google.cloud.bigquery.client.Client.html

For example, in the tutorial: what is the difference between these 2 table objects created?

table = bigquery.Table(table_id, schema=schema)
table = client.create_table(table)  # Make an API request.

[HemangChothani]

@darwinyip Description of the following statements:

 table = bigquery.Table(table_id, schema=schema)   
# This statement creates a table class object locally which you need pass to `create_table` method to create your table 

table = client.create_table(table)
# This statement sent a request to the server to create a table in BigQuery database and return the table object with it's properties and information

Example:
table.created   # it gives the datetime of table creation
table.etag  # gives the Etag of table
table.num_rows  # gives the number of rows in table
table.full_table_id  # full id of table including project and dataset.

[HemangChothani]

@darwinyip Did above explanation helped you?

[darwinyip]

@HemangChothani Yes it did. Thank you. However main issue I am raising is the lack of documentation around it.

[HemangChothani]

@darwinyip Is you concern related to type hints, types to method params.

[HemangChothani]

Should i mention return type of all the public methods of all the classes?

Edit: Should we include pytype nox.py file to check type hints and return type as included in firestore