Add Ergo‑L keycodes and sendstring

[trilowy]

Description

Add keycodes and sendstring for the French Ergo‑L layout.

I used this command to generate the keymap_ergol.h:

qmk generate-keycode-extras --version latest --lang ergol -o quantum/keymap_extras/keymap_ergol.h

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[trilowy]

I have a question, if it does not cause a breaking change, should I merge it against master instead of develop?

[zvecr]

It's still a core change, so needs to target develop.