Add I2C transaction api

[i404788]

Still untested at the moment but I've added eh1 and eh0.2 I2C transaction API to the I2C peripheral, this can also be used to implement proper write_read (see #848).

Some notes:

• I'm currently not pre-filling the FIFO like is done in the perform_write
• Command and data parts are split up because of the blocking nature of filling/emptying the FIFOs, could make it harder to debug issues but from the command API it seems like you aren't supposed to gradually load commands while it's being processed; let me know if that's a wrong assumption.
• I've not validated that all the commands are like the I2C events contract yet
• I've used the structure from https://github.com/stm32-rs/stm32f4xx-hal/blob/master/src/i2c.rs#L566 although it ended up very different in the implementation.

Must

• The code compiles without errors or warnings.
• [?] All examples work.
• cargo fmt was run.
• Your changes were added to the CHANGELOG.md in the proper section.
• You updated existing examples or added examples (if applicable).
• Added examples are checked in CI

Nice to have

• You add a description of your work to this PR.
• You added proper docs for your newly added features and code.

[MabezDev]

Thanks for the PR! It would be really nice to support the transaction API.

I'm not a huge fan of the macro approach, I'd really like to avoid it unless there isn't another way.

Perhaps we should define our own Operation enum, and add From impls for the two versions of ehal?

[jessebraham]

Hey @i404788, just checking in; are you able to completing this PR, or would you like us to try to find somebody to wrap it up instead?

[jessebraham]

Thank you regardless for your contribution, but I am going to close this PR for now. Please feel free to revive it or open a new one if you manage to find some time to come back to this, otherwise hopefully somebody else can carry on with this work in the future.