feat: Add configurations and avoid hardcoding REST urls, network names, etc.

[MalteHerrmann]

This PR adds a new configuration approach that uses a NetworkConfig and an UpgradeConfig instead of having the Evmos-related information hardcoded and then read depending on Local Node, Testnet or Mainnet.

[todo-pr-checker]

There are 13 unresolved action items in this Pull Request:

README.md (1 action item):

proposer/README.md

Lines 14 to 15 in 5de2fad

	<!-- TODO: this whole thing needs to be adjusted to avoid the specific steps for the outdated Evmos implementation -->

src/appd.rs (1 action item):

proposer/src/appd.rs

Lines 6 to 7 in 5de2fad

	///
	/// TODO: check if this can be removed

src/cli.rs (3 action items):

proposer/src/cli.rs

Lines 36 to 37 in 5de2fad

	///
	/// TODO: enable using e.g. claude or cursor-agent in headless mode

proposer/src/cli.rs

Lines 53 to 54 in 5de2fad

	///
	/// TODO: this should be updated to use the new Cosmos SDK v50 based approach of the

proposer/src/cli.rs

Lines 70 to 71 in 5de2fad

	// TODO: remove commonwealth logic.

src/config.rs (3 action items):

proposer/src/config.rs

Lines 17 to 18 in 5de2fad

	pub target_time_utc: String,
	// TODO: potentially remove going forward

proposer/src/config.rs

Lines 40 to 41 in 5de2fad

	///
	/// TODO: This should eventually read from YAML.

proposer/src/config.rs

Lines 87 to 88 in 5de2fad

	name: "Noble Mainnet".into(),
	// TODO: use $HOME instead and expand, but doesn't work like that out of the box but

src/helper.rs (2 action items):

proposer/src/helper.rs

Lines 118 to 119 in 5de2fad

	///
	/// TODO: this is currently doing too much, the summary etc. should be optional and not hardwired.

proposer/src/helper.rs

Lines 158 to 159 in 5de2fad

	&config::UpgradeConfig {
	// TODO: get upgrade name from user

src/inputs.rs (1 action item):

proposer/src/inputs.rs

Lines 142 to 143 in 5de2fad

	//
	// TODO: rather we should get the input for the target update time.

src/network.rs (1 action item):

proposer/src/network.rs

Lines 4 to 5 in 5de2fad

	///
	/// TODO: should be removed

src/proposal.rs (1 action item):

proposer/src/proposal.rs

Lines 9 to 10 in 5de2fad

	///
	/// TODO: this can be removed or moved to another tool / maybe a plugin type thing

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