feat: tests and bug fixes AgentState.state

[cpacker]

Please describe the purpose of this pull request.

Another attempt to patch #966 (closes #966)

• add tests for read/writes on AgentState.state
  • added to tests/test_metadata_store.py (maybe should be put elsewhere?)
• in case of an empty agent_state.state, read from the preset instead
• add tests for loading with empty agent_state.state (should no longer error)
• remove create_agent_from_preset, instead modify Agent.__init__ to take optional preset arg

How to test

• reproduce linked issue
• confirm that this PR patches the issue

Have you tested this PR?

Repro issue (0.3.3)

Roll back to version 0.3.3:

git checkout 508679e
poetry install

Wipe existing home dir:

mv ~/.memgpt ~/.memgpt_backup

Try to repro based on #1070:

memgpt quickstart

📖 MemGPT configuration file updated!
🧠 model        -> ehartford/dolphin-2.5-mixtral-8x7b
🖥️  endpoint     -> https://api.memgpt.ai
⚡ Run "memgpt run" to create an agent with the new config.

memgpt run

  File "/Users/loaner/dev/MemGPT-2/memgpt/cli/cli.py", line 620, in run
    memgpt_agent = presets.create_agent_from_preset(
  File "/Users/loaner/dev/MemGPT-2/memgpt/presets/presets.py", line 82, in create_agent_from_preset
    assert preset_name == preset.name, f"AgentState preset '{preset_name}' does not match preset name '{preset.name}'"
AttributeError: 'NoneType' object has no attribute 'name'

Repro issue (main)

Roll back to version to main (pre-PR #1058):

git checkout main
poetry install

Wipe existing home dir:

mv ~/.memgpt ~/.memgpt_backup

Try to repro based on #1070:

memgpt quickstart

📖 MemGPT configuration file updated!
🧠 model        -> ehartford/dolphin-2.5-mixtral-8x7b
🖥️  endpoint     -> https://api.memgpt.ai
⚡ Run "memgpt run" to create an agent with the new config.

memgpt run

🧬 Creating new agent...
->  🤖 Using persona profile 'sam_pov'
->  🧑 Using human profile 'basic'
🎉 Created new agent 'BenevolentUnicorn' (id=8cf1de2c-6861-404b-abde-cc39f0269db2)

Hit enter to begin (will request first MemGPT message)

@sarahwooders bug reported in #1070 was fixed sometime past the 0.3.3 tag, but pre-this PR.

Confirm that PR patches the issue Ensuring that there was no regression in this PR

memgpt quickstart

📖 MemGPT configuration file updated!
🧠 model        -> ehartford/dolphin-2.5-mixtral-8x7b
🖥️  endpoint     -> https://api.memgpt.ai
⚡ Run "memgpt run" to create an agent with the new config.

memgpt run

🧬 Creating new agent...
->  🤖 Using persona profile 'sam_pov'
->  🧑 Using human profile 'basic'
🎉 Created new agent 'LovingNachos' (id=3633e9a0-ad69-4dd0-b0d7-2e53f3b1c000)

Hit enter to begin (will request first MemGPT message)

[sarahwooders]

lgtm!