implement cass_table_meta_column

[muzarski]

The order of table columns in cpp-driver (and in DESCRIBE KEYSPACE from cqlsh):

1. pk columns sorted by position
2. ck columns sorted by position
3. remaining columns sorted alphabetically

This is exactly how I implemented cass_table_meta_column.

My only concern is that every time the column is not a part of neither pk nor ck, we need to allocate a vector representing the remaining columns, and sort it. I wonder if it's worth adding such vector to CassTableMeta, so we do that only one time.

Advantage of other solution is obviously that we increase the performance of cass_table_meta_column - I'm not sure how often this method is called by the users.
Disadvantage is that we need to store another vector for each table metadata. It means more memory consumption by metadata structs, which is already big enough.

Pre-review checklist

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• PR description sums up the changes and reasons why they should be introduced.
• [ ] I have implemented Rust unit tests for the features/changes introduced.
• I have enabled appropriate tests in .github/workflows/build.yml in gtest_filter.
• I have enabled appropriate tests in .github/workflows/cassandra.yml in gtest_filter.

[muzarski]

v1.1: Changed EXPECT_EQ to ASSERT_EQ in test.

[muzarski]

v1.2: Addressed review comments