CHIA-595: bump chia_rs to 0.8.0 and update G1Element handling

[arvidn]

Purpose:

bump the chia_rs dependency to use the latest version.

The new version returns G1Elements in Spend and SpendBundleConditions as parameters to the AGG_SIG_* conditions. This has two consequences in chia-blockchain:

1. We no longer need to convert the bytes48 objects into G1Elements when we get them back from block validation.
2. The public keys are now more strictly validated on the rust side. Converting 48 bytes into a G1Element (public key) may fail, if the bytes are not a valid serialization of a valid key.

So, some tests that used garbage bytes in place of a public key had to be updated to use valid keys.

Also, the BLS cache no longer needs to take the keys in byte-form, but can take them as G1Elements directly.

Current Behavior:

The BLS cache takes keys as plain bytes.
The KeyTool (test utility) uses serialized public keys as index.
The pkm_pairs() function returns public keys as bytes48.

New Behavior:

The BLS cache takes keys as G1Elements
The KeyTool uses G1Element as index.
The pkm_pairs() function returns public keys as G1Element.

[github-actions]

File	Coverage	Missing Lines
chia/_tests/util/key_tool.py	80.0%	lines 25

Total	Missing	Coverage
132 lines	Unknown	99%