ci: Miscellaneous improvements

[Ouss4]

1. Cache downloaded tools.
2. Cancel duplicate jobs.
3. Use current repo when linking the core, this allows users to test their code when creating PRs against their forks (for instance an error in an example sketch will build successfully in a fork workflow.)
4. Cache Arduino IDE.
5. Add workflow_dispatch to be able to trigger the workflow manually.

[me-no-dev]

it is not necessary that the target mcu equals the third part of FQBN. This in our case currently is true, but if we want to test agains different boards (we will in near future) then scripts will not be able to tell what is the actual MCU and decide to skip the test.

[Ouss4]

it is not necessary that the target mcu equals the third part of FQBN. This in our case currently is true, but if we want to test agains different boards (we will in near future) then scripts will not be able to tell what is the actual MCU and decide to skip the test.

How would this look like? espressif:esp32:esp32-devkitc for instance? What would the second part represent in this case?

[me-no-dev]

first part is "manufacturer"m, second is "core" and third is the board. manufacturer and core come from the path of installation: ~/Arduino/hardware/[manufacturer]/[core]

[Ouss4]

first part is "manufacturer"m, second is "core" and third is the board. manufacturer and core come from the path of installation: ~/Arduino/hardware/[manufacturer]/[core]

Okay, thanks. If the boards we want to test against are Espressif's, we can still extract the chip name from the board's, but other manufacturers won't necessary follow the same naming conventions (and I think we also have few special cases).
I will drop this commit.