runners: jlink: Add support for big endian device

[sigmundklaa]

Adds the --endian option, setting endianness for both the JLink and the GDB server.

Documented at:
https://wiki.segger.com/J-Link_Commander#LE
https://wiki.segger.com/J-Link_GDB_Server#-endian

[henrikbrixandersen]

@sigmundklaa You need to fix your Git commit message:

1: UC2 Signed-off-by: must have a full name
Error: See https://docs.zephyrproject.org/latest/contribute/guidelines.html#commit-guidelines for more details

aba8cc45349f6249a74b1e926b0e8799582acbc9: author email (sigmundklaa [email protected]) does not follow the syntax: First Last .

[github-actions]

Hi @sigmundklaa!
Congratulations on getting your very first Zephyr pull request merged 🎉🥳. This is a fantastic achievement, and we're thrilled to have you as part of our community!

To celebrate this milestone and showcase your contribution, we'd love to award you the Zephyr Technical Contributor badge. If you're interested, please claim your badge by filling out this form: Claim Your Zephyr Badge.

Thank you for your valuable input, and we look forward to seeing more of your contributions in the future! 🪁