feat: --read-only flag to disable write tools

[kskarthik]

Introduces a new --read-only command-line flag. When set to this flag, disables all tools that can modify bug states, ensuring the server operates in a read-only capacity.

[kskarthik]

@lemenkov JFYI

This feature filters the methods which modify a bug via tool tags property. In case, you want to add more tools which alter bugs, please keep that in mind.

Also, this feature overlaps with the MCP_BUGZILLA_DISABLED_METHODS

currently, my thought is:

1. check if MCP_BUGZILLA_DISABLED_METHODS  is set,
2. if yes, do not call the disable_write_components function

This way it is simpler and easier for user & us to maintain. don't let the user mix both options

[kskarthik]

Surprisingly, having both options does not have any side effects in the program.

Maybe we can allow it side by side. Let me test it further,

[lemenkov]

Both methods looks good (env-var and cli switch). Although MCP_BUGZILLA_DISABLED_METHODS looks more fine-grained I really don't see a reason to selectively disable any RO-methods. From my understanding disabling RW-methods makes much more sense in some configurations while selecting RO-metholds doesn't add up. But anyway I'm fine with both approaches.