feat: add `fuel-toolchain.toml` to `create fuels` template

[danielbate]

• Closes #2426

This PR:

• Adds the fuel-toolchain.toml file to the next template
• Introduces a test to validate the versions we ship with it

[github-actions[bot]]

Coverage Report:

Lines	Branches	Functions	Statements
80.29%(+0%)	71.8%(+0%)	77.56%(+0%)	80.36%(+0%)

Changed Files:

Coverage values did not change👌.