perf: improve performance of project.get_contract()

[antazoey]

What I did

The performance of getting contracts from projects is bad because it pointlessly always reloaded the manifest. Mistake! Fixed!

For testing, using a MASSIVE PROJECT.

With change:

In [1]: %time project.get_contract("MyContract")
CPU times: user 116 ms, sys: 12 ms, total: 128 ms
Wall time: 132 ms

Without change:

In [1]: %time project.get_contract("MyContract")
CPU times: user 1min 19s, sys: 2.88 s, total: 1min 22s
Wall time: 1min 22s

Improvement≈99.84%

So, the performance improvement is approximately 99.84%.

How I did it

delete code.
test.

How to verify it

Checklist

• All changes are completed
• New test cases have been added
• Documentation has been updated