[flowstate_ros_bridge] Make page_size and other params configurable in ExecutiveBridge

[Yadunund]

The flowstate_ros_bridge queries the Flowstate Solution Servce to get a list of BTs. See here. The default request params will only query 20 BTs as seen here. Another area where page_size is used is querying the execute for a list of running operations using this proto.

If your solution had more than 20 BTs, calling the service to list the behavior trees would return a truncated list.

This PR

• Makes the page_size configurable and by default sets it to the max value.
• Makes some other executive parameters configurable.
• Ran clang linter on flowstate_ros_bridge which adds some formatting changes.

[mjcarroll]

LGTM with small nits

[Yadunund]

Discussed this with @luca-della-vedova who suggested relying on next_page_token to recursively get all pages. We change the arg to std::optional<std::size_t> with default nullopt.

[luca-della-vedova]

Actually upon further thought I feel we should remove the parameter altogether and instead:

• In the clear_and_delete_operations here, always iterate through all operations. The function's API promises to delete all currently running operations, deleting only one page goes against that.
• In the behavior_trees here, either do the same as the above or make it a function parameter with default value, i.e.:

// Current
absl::StatusOr<std::vector<BehaviorTree>> behavior_trees() const;
// After, return the first `n` or all the behavior trees.
absl::StatusOr<std::vector<BehaviorTree>> behavior_trees(std::optional<std::size_t> n = std::nullopt) const;

But still my recommendation would still be to remove it altogether since it's not clear what the ordering of the behavior trees returned would be, and "first n" might mean anything from "alphabetical order", "last edit order", "creation order", non-guaranteed order, and unless we can guarantee a fixed ordering users should probably not rely on it.

[luca-della-vedova]

@Yadunund This is an implementation of the approach where we always get all running operations and behavior trees 4142ba3