Database software type value input should be more flexible

[fernando-villalba]

Issue

Running the following command:

civo database create db-psql --software psql

Gives this output:

Please check if you are using the latest version of CLI and retry the command 
If you are still facing issues, please report it on our community slack or open a GitHub issue (https://github.com/civo/cli/issues) 
Error: The provided software name is not valid. Make sure you use correct capitalization (e.g. MySQL, PostgreSQL)

Aside from the generic error which is useless in this scenario, there are a couple of issues here:

1. The values that can be provided here should be more flexible.

They should not be case sensitive, and they should accept shorthand form of the db name. For example it should accept postgresql as well as PostgreSQL and psql and PSQL. This would make the usage more intuitive.

2. The --software flag is a little strange, wouldn't --type be more fitting?

This one is as big of a deal, but I feel that the conceptual model of the user is more inclined to use --type as a flag for this than --software

Acceptance Criteria

• Accept shorthands for databases and make the names case insensitive.
• Reconsider the name of the flag --> Not as important, required to close this ticket.