feat: Add new private_key & passphrase based authentication method (#38)

# Description

The tap can now connect to snowflake using a provided private key and
passphrase. The private key can be provided as a string or the path to
the private key file can be provided.

Fixes an edge-case handling where schemas needing quotes (example:
`"MySpecial.SchemaName"`) are properly handled during discovery.

Speeds up discovery slightly when `tables` is provided. The speed up is
achieved by only inspecting relevant schemas which can be derived by
parsing each table within `tables`.

Introduces 3 new config parameters to support key based authentication
and since there are 2 ways to authenticate, `password` is now an
optional parameter. The new parameters are:
- `private_key`
- `private_key_path`
- `private_key_passphrase`

resolves: #19

---------

Co-authored-by: Edgar Ramírez Mondragón <[email protected]>

README.md

@@ -29,7 +29,13 @@ environment variable is set either in the terminal context or in the `.env` file
 
 ### Source Authentication and Authorization
 
-Standard `username` and `password` auth is supported.
+This tap supports two authentication methods:
+- Standard `username` and `password` auth
+- [Key Pair Authentication](https://docs.snowflake.com/en/user-guide/key-pair-auth)
+
+#### Key Pair Authentication
+
+Key Pair authentication can be enabled by specifing either the `private_key` of the `private_key_path`, and optionally the `private_key_passphrase` if required.
 
 ### Enabling Batch Messaging
 

meltano.yml

@@ -14,6 +14,14 @@ plugins:
     - name: user
     - name: password
       kind: password
+      sensitive: true
+    - name: private_key
+      kind: password
+      sensitive: true
+    - name: private_key_path
+    - name: private_key_passphrase
+      kind: password
+      sensitive: true
     - name: account
       kind: password
     - name: role